To start off, here are Krull's stats and abilities

(based on in-game info, not the vainglory site itself)

KRUL: lvl 1 lvl 12 per level
health: 643 1501 +78
energy: 220 506 +26
weapon: 68 139 +6/+7
atk speed: 100% 136% +3/4%
armor: 20 75 +5
shield: 20 75 +5
range: 1.5 1.5 +0
move speed: 3.4 3.4 +0

if you're curious about the amount of weapon power you get, here is it:
(lvl 1 - 12) 68-74-81-87-94-100-107-113-120-126-133-139
same for attack speed:
(lvl 1 - 12) 100%-103%-107%-110%-113%-117%-120%-123%-126%-130%-133%-136%

HEROIC PERK: SHADOWS EMPOWER ME
when you're in a brush for 1.5 seconds you gain +2 move speed and a slow (-40%) on your next basic attack for 3 seconds after leaving a brush. this ability won't help you escape from fights because it resets when taking damage or dealing damage, however this ability is very good when used to get into a fight. not only does it give you a speed boost but the enemy you hit gets slowed, making it much easier to stay close and heal up from hitting him

DEAD MAN'S RUSH
KRUL: lvl 1 lvl 5 per level overdrive
type: targeted targeted - -
range: 4.5 4.5 +0 +0
energy cost: 45 65 +5 +5
cooldown: 12 8 -1 -1
basic attack damage: 160% 160% +0% +0%
crystal damage: 0 0 +0 +0 (70%)
barrier: 100 350 +50 +100 (125%)
duration: 2.5 2.5 +0 +0 (0.2%)

not only does it deal 160% basic attack damage, but it also counts as a basic attack, meaning all effects that get applied with basic attacks (1 of Krul's SPECTRAL SMITE stacks, bonesaw stack, shiversteel slow) also work using this ability. overall a good way to jump into a fight, get close to an enemy or to survive fights longer

SPECTRAL SMITE
KRUL: lvl 1 lvl 5 per level overdrive
type: targeted targeted - -
range: 3.7 3.7 +0 +0
energy cost: 45 65 +5 +5
cooldown: 13 10 -0.5 -1.5
damage: 100 350 +50 +100 (50%)
damage/stack: 20 95 +15 +30 (20%)
heal: 40 140 +20 +40 (35%)
heal/stack: 15 40 +5 +10 (20%)
weapon lifesteal/stack: 10% 12% +0% +2%

okay there is alot to say about this ability so sit back and read it through, because without an understanding of this ability you can't play Krul

this ability has a passive:
basic attacks and abilities apply weakness for 4 seconds (up to 8 stacks). each stack reduces the target's damage by 6.2% (up to 49.6%) and increases Krul's lifesteal against the weakened target

the activate ability:
activate all stacks to deal damage and heal based on the amount of stacks

the ability applies stacks which provide you with healing per stack. this ability is best used when its... not used... when you trigger the ability you use up all stacks, when you're in a fight your purpose is to distract, survive and kill off anyone who stays in the fight to long. without your stacks your healing is VERY low. if you don't use the ability you will survive much longer and only use the ability when you're really about to die (and run away after using it) or when an enemy is gonna run away. the ability does a burst damage and heal that can give you a chance to stick to another enemy or to kill off the enemy you were attacking.

FROM HELL'S HEART
KRUL: lvl 1 lvl 3 per level
type: untargeted untargeted -
range: 13.5 13.5 +0
energy cost: 55 85 +15
cooldown: 80 50 -15
damage: 350 650 +150 (100%)
slow duration: 3 4 +0.5
stun duration: 1.8 2.2 +0.2

when used a sword will be thrown in the direction of your choosing. after it hit its longest range, it will go back towards Krul. its damage and stun time are based on the amount of time the sword has travelled, 50% on point black range, 100% at max range and up to 150% when returning to Krul.

I'll start with calculating the amount of damage each ability does, as well as the amount of healing or barrier it gives

lvl 1:

DEAD MAN'S RUSH:
160% basic attack damage = (I will be using the amount of base weapon power on lvl 1) 68 : 100 x 160 = 108.8 weapon power damage
cooldown: 12 seconds
108.8 | 12
:12 | :12
9.1 | 1
9.1 weapon power damage per second if you were to use this ability instantly when it's available

barrier: 100
cooldown: 12 seconds
100 | 12
:12 | :12
8.3 | 1
8.3 barrier health per second if you were to use this ability instantly when it's available

SPECTRAL SMITE:
without stacks:
100 crystal power damage
cooldown: 13
100 | 13
:13 | :13
7.7 | 1
7.7 crystal power damage per second if you were to use this ability instantly when it's available

40 healing
cooldown: 13 seconds
40 | 13
:13 | :13
3.1 | 1
3.1 healing per second if you were to use this ability instantly when it's available

with all 8 stacks:
damage: 100 + 20 x 8 = 260 crystal power damage
cooldown: 13 seconds
260 | 13
:13 | :13
20 | 1
20 crystal power damage per second if (only with 8 stacks of course) you use this ability instantly when it's available

healing: 40 + 15 x 8 = 160 healing
cooldown: 13 seconds
160 | 13
:13 | :13
12.3 | 1
12.3 healing per second if (only with 8 stacks) you were to use this ability instantly when it's available

lifesteal: 10% x 8 = 80% basic attack lifesteal

per stack:
+20 crystal power damage (when you use this ability)
+15 healing (when you use this ability)
+10% lifesteal on your basic attacks

DEAD MAN'S RUSH (lvl 1)
damage: 108.8 weapon power damage
cooldown: 12 seconds
barrier: 100 barrier health
barrier time (how long the barrier stays): 2.5 seconds
damage per second: 9.1 weapon power damage
barrier per second: 8.3 barrier health

SPECTRAL SMITE (lvl 1)
without stacks:
damage: 100 crystal power damage
cooldown: 13 seconds
healing: 40 healing
damage per second: 7.7 crystal power damage
healing per second: 3.1 healing
with all 8 stacks:
damage: 260 crystal power damage
cooldown: 13 seconds
healing: 160 healing
lifesteal: 80% basic attack lifesteal
damage per second: 20 crystal power damage
healing per second: 12.3 healing
per stack:
damage: +20 crystal power damage (when you use this ability)
healing: +15 healing (when you use this ability)
lifesteal: +10% basic attack lifesteal

on lvl 1 I recommend you take SPECTRAL SMITE over DEAD MAN'S RUSH because of the lifesteal on basic attacks and the damage that goes up the longer you wait with using the ability

lvl 4:

DEAD MAN'S RUSH:
160% basic attack damage = (I am gonna use the lvl 7 basic attack damage because it's the lowest level on which you can get this ability to lvl 4) 107 : 100 x 160 = 171.2 weapon power damage
cooldown: 12 - 1 x (lvl - 1) = 12 - 3 = 9 seconds
171.2 | 9
:9 | :9
19 | 1
19 weapon power damage per second if you were to use this ability instantly when it's available

barrier: 100 + 50 x (lvl - 1) = 100 + 150 = 250 barrier health
cooldown: 9 seconds
250 | 9
:9 | :9
27.8 | 1
27.8 barrier health per second if you were to use this ability instantly when it's available

SPECTRAL SMITE:
without stacks:
damage: 100 + 50 x (lvl - 1) = 100 + 150 = 250 crystal power damage
cooldown: 13 - 0.5 x (lvl - 1) = 13 - 1.5 = 11.5 seconds
250 | 11.5
:11.5 | :11.5
21.7 | 1
21.7 crystal power damage per second if you were to use this ability instantly when it's available

healing: 40 + 20 x (lvl - 1) = 40 + 60 = 100 healing
cooldown: 11.5 seconds
100 | 11.5
:11.5 | :11.5
8.7 | 1
8.7 healing per second if you were to use this ability instantly when it's available

with all 8 stacks:
damage: 100 + 50 x (lvl - 1) + (20 + 15 x (lvl - 1)) x 8 = 100 + 150 + 65 x 8 = 250 + 520 = 770 crystal power damage
cooldown: 11.5 seconds
770 | 11.5
:11.5 | :11.5
67 | 1
67 crystal power damage per second if (only with 8 stacks) you were to use this ability instantly when it's available

healing: 40 + 20 x (lvl - 1) + (15 + 5 x (lvl - 1)) x 8 = 40 + 60 + 30 x 8 = 100 + 240 = 340 healing
cooldown: 11.5 seconds
340 | 11.5
:11.5 | :11.5
30 | 1
30 healing per second if (only with 8 stacks) you were to use this ability instantly when it's available

lifesteal: 10% x 8 = 80% basic attack lifesteal

per stack:
damage: 20 + 15 x (lvl - 1) = +65 crystal power damage (when you use this ability)
healing: 15 = 5 x (lvl - 1) = +30 healing (when you use this ability)
lifesteal: +10% lifesteal on your basic attacks

DEAD MAN'S RUSH (lvl 4)
damage: 171.2 weapon power damage
cooldown: 9 seconds
barrier: 250 barrier health
barrier time (how long the barrier stays): 2.5 seconds
damage per second: 19 weapon power damage
barrier per second: 27.8 barrier health

SPECTRAL SMITE (lvl 4)
without stacks:
damage: 250 crystal power damage
cooldown: 11.5 seconds
healing: 100 healing
damage per second: 21.7 crystal power damage
healing per second: 8.7 healing
with all 8 stacks:
damage: 770 crystal power damage
cooldown: 11.5 seconds
healing: 340 healing
lifesteal: 80% basic attack lifesteal
damage per second: 67 crystal power damage
healing per second: 30 healing
per stack:
damage: +65 crystal power damage (when you use this ability)
healing: +30 healing (when you use this ability)
lifesteal: +10% basic attack lifesteal

I don't know what to say, these numbers are proof that SPECTRAL SMITE is much stronger than DEAD MAN'S RUSH. in any case even if you were to go weapon power, the weapon power % ratio on DEAD MAN'S RUSH stays the same on every level so a lvl 1 DEAD MAN'S RUSH would do the same amount of damage as it would on lvl 4 with both weapon and crystal power. also the barrier from DEAD MAN'S RUSH can't match the healing from SPECTRAL SMITE

lvl 5:

DEAD MAN'S RUSH:
damage: 160% basic attack damage = (lvl 12 basic attack damage) 139 : 100 x 160 = 222.4 weapon power damage
cooldown: 8 seconds
222.4 | 8
:8 | :8
27.8 | 1
27.8 weapon power damage per second if you were to use this ability instantly when it's available

barrier: 350 barrier health
cooldown: 8 seconds
350 | 8
43.8 | 1
43.8 barrier health per second if you were to use this ability instantly when it's available

SPECTRAL SMITE:
without stacks:
damage: 350 crystal power damage
cooldown: 10 seconds
350 | 10
:10 | :10
35 | 1
35 crystal power damage per second if you were to use this ability instantly when it's available

healing: 140 healing
cooldown: 10 seconds
140 | 10
:10 | :10
14 | 1
14 healing per second if you were to use this ability instantly when it's available

with all 8 stacks:
damage: 350 + 95 x 8 = 1110 crystal power damage
cooldown: 10 seconds
1110 | 10
:10 | :10
111 | 1
111 crystal power damage per second if (only with 8 stacks) you were to use this ability instantly when it's available

healing: 140 + 40 x 8 = 460 healing
cooldown: 10 seconds
460 | 10
:10 | :10
46 | 1
46 healing per second if (only with 8 stacks) you were to use this ability instantly when it's available

basic attack lifesteal: 12% x 8 = 96% basic attack lifesteal

per stack:
damage: +95 crystal power damage (when you use this ability)
healing: +40 healing (when you use this ability)
lifesteal: +12% lifesteal on your basic attacks

DEAD MAN'S RUSH (lvl 5)
damage: 222.4 weapon power damage
cooldown: 8 seconds
barrier: 350 barrier health
barrier time (how long the barrier stays): 2.5 seconds
damage per second: 27.8 weapon power damage
barrier per second: 43.8 barrier health

SPECTRAL SMITE (lvl 5)
without stacks:
damage: 350 crystal power damage
cooldown: 10 seconds
healing: 140 healing
damage per second: 35 crystal power damage
healing per second: 14 healing
with all 8 stacks:
damage: 1110 crystal power damage
cooldown: 10 seconds
healing: 460 healing
lifesteal: 96% basic attack lifesteal
damage per second: 111 crystal power damage
healing per second: 46 healing
per stack:
damage: +95 crystal power damage (when you use this ability)
healing: +40 healing (when you use this ability)
lifesteal: +12% basic attack lifesteal

if you wish to take the 3th upgrade for your ultimate, which I do not recommend, I highly advise you to take the fifth level for SPECTRAL SMITE. SPECTRAL SMITE is stronger than DEAD MAN'S RUSH in every way.

the big question, what to overdrive?

I recommend you take both overdrives over the third level for the ultimate, otherwise take the overdrive for SPECTRAL SMITE over DEAD MAN'S RUSH's overdrive.

pros and cons for every overdrive:

DEAD MAN'S RUSH:
-energy cost up from 60 to 65 energy
-cooldown down from 9 to 8 seconds
-barrier health up from 250 to 350 barrier health
-crystal power increases barrier health (125% crystal ratio) and the amount of time the barrier stays up (0.2% crystal ratio)
-has a crystal ratio of 70% (1 crystal power = +0.7 crystal damage, 100 crystal power = +70 crystal damage) but no base crystal power

SPECTRAL SMITE:
-energy cost up from 60 to 65 energy
-cooldown down from 11.5 to 10 seconds
-crystal power damage up from 250 to 350 crystal power damage
-damage/stack up from 65 to 95 extra crystal power damage per stack when activated
-healing up from 100 to 140 healing
-healing/stack up from 30 to 40 healing per stack when activated
-weapon lifesteal up from 10%/stack to 12%/stack (from 80% to 96% lifesteal with 8 stacks)
-crystal power damage has a 50% crystal ratio
-damage/stack and healing/stack has a 20% crystal ratio
-base healing has a 35% crystal ratio

FROM HELL'S HEART
-energy cost up from 70 to 85 energy
-cooldown down from 65 to 50 seconds
-damage up from 500 to 650 crystal power damage
-slow duration up from 3.5 to 4 seconds
-slow duration up from 2 to 2.2 seconds
-damage has a 100% crystal ratio

I will see how strong both 100 weapon and 100 crystal power is with all abilities on lvl 1 and 5 (ult lvl 1 and 3). this should give you an idea of the strengths of both weapon and crystal power.

DEAD MAN'S RUSH with 100 weapon power:
KRUL: lvl 1 lvl 5 effect from 100 weapon power
type: targeted targeted
range: 4.5 4.5
energy cost: 45 65
cooldown: 12 8
basic attack damage: 160 160 (+160)
crystal damage: 0 0
barrier: 100 350
duration: 2.5 2.5

DEAD MAN'S RUSH with 100 crystal power:
KRUL: lvl 1 lvl 5 effect from 100 crystal power
type: targeted targeted
range: 4.5 4.5
energy cost: 45 65
cooldown: 12 8
basic attack damage: 0 0
crystal damage: 70 70 (+70)
barrier: 225 475 (+125)
duration: 2.7 2.7 (+0.2)

there is a clear difference in the amount of damage (160/70), but you can also see that with crystal power the barrier gets much bigger (+125 barrier health) and lasts a little bit longer (+0.2 seconds)

in this situation, if you want more damage -> go weapon power, if you want more health (in this case in the form of a barrier) -> go crystal power

SPECTRAL SMITE with 100 weapon power and without any stacks:
KRUL: lvl 1 lvl 5 effect from 100 weapon power
type: targeted targeted
range: 3.7 3.7
energy cost: 45 65
cooldown: 13 10
damage: 100 350
damage/stack: 20 95
total damage: 100 350
heal: 40 140
heal/stack: 15 40
total healing: 40 140
weapon lifesteal (passive): 0% 0%

SPECTRAL SMITE with 100 crystal power and without any stacks:
KRUL: lvl 1 lvl 5 effect from 100 crystal power
type: targeted targeted
range: 3.7 3.7
energy cost: 45 65
cooldown: 13 10
damage: 150 400 (+50)
damage/stack: 40 115 (+20)
total damage: 150 400 (+50)
heal: 75 175 (+35)
heal/stack: 35 60 (+20)
total healing: 75 175 (+35)
weapon lifesteal (passive): 0% 0%

you can see very quickly, weapon power doesn't make a difference here. but wait, what if we were to see the ability with all 8 stacks:

SPECTRAL SMITE with 100 weapon power and with all 8 stacks:
KRUL: lvl 1 lvl 5 effect from 100 weapon power
type: targeted targeted
range: 3.7 3.7
energy cost: 45 65
cooldown: 13 10
damage: 100 350
damage/stack: 20 95
total damage: 260 1110
heal: 40 140
heal/stack: 15 40
total healing: 160 460
weapon lifesteal (passive): 80% 96%
basic attack healing from passive: 80 96 (+80/+96)

SPECTRAL SMITE with 100 crystal power and with all 8 stacks:
KRUL: lvl 1 lvl 5 effect from 100 crystal power
type: targeted targeted
range: 3.7 3.7
energy cost: 45 65
cooldown: 13 10
damage: 150 400 (+50)
damage/stack: 40 115 (+20)
total damage: 470 1320 (+210)
heal: 75 175 (+35)
heal/stack: 35 60 (+20)
total healing: 355 655 (+195)
weapon lifesteal (passive): 80% 96%
basic attack healing from passive: 0 0

this clearly shows that the damage is stronger with crystal power (lvl 1: 260/470, lvl 5: 1110/1320), just like the healing (lvl 1: 160/355, lvl 5: 460/655), however your passive healing (per basic attack) becomes useless (lvl 1: 80/0, lvl 5: 96/0)

in this situation, if you want more burst damage and heal -> go crystal power, if you want more sustain healing -> go weapon power

FROM HELL'S HEART with 100 weapon power:
KRUL: lvl 1 lvl 3 effect from 100 weapon power
type: untargeted untargeted
range: 13.5 13.5
energy cost: 55 85
cooldown: 80 50
damage: 350 650
slow duration: 3 4
stun duration: 1.8 2.2

FROM HELL'S HEART with 100 crystal power:
KRUL: lvl 1 lvl 3 effect from 100 crystal power
type: untargeted untargeted
range: 13.5 13.5
energy cost: 55 85
cooldown: 80 50
damage: 450 750 (+100)
slow duration: 3 4
stun duration: 1.8 2.2

as you can see, only crystal power effects this ability. the damage from the ability goes up with 100 crystal power damage compared to weapon power (lvl 1: 350/450, lvl 3: 650/750)

in this situation, if you want more burst damage -> go crystal power, if you want more sustain damage (basic attacks get stronger from weapon power) -> go weapon power

Which is better for Krul, weapon or crystal power?

I will be honest and say I have never actually used crystal power as a Krul, so I can't tell you the truth, however I can tell you that weapon power is very strong in long battles and gives you a lot of sustain heal and damage as long as you can stick to your enemies. I can however say that after looking into the numbers of Krul, crystal power seems more like a hit-and-run build in which you quickly jump in with your DEAD MAN'S RUSH, do 8 basic attacks, activate your SPECTRAL SMITE and run away

I wish to look at my items and compare them to other items:

PINK: utility items, these items can do all sorts of things
LIGHT YELLOW: items best used against crystal power enemies
DARK YELLOW: items best used against weapon power enemies
GREEN: health items purely for the extra health to survive fights longer
RED: items to gain extra basic attack damage
BLUE: items to gain extra ability damage (not used in these builds)

(->) = improvement from my recommended item
(->) = same as my recommended item or have completely different uses
(->) = worse than my recommended item

starting with sorrowblade

(this is only in my assassin build)

+150 extra damage

good for 2 things:
-your enemy dies much faster
-your breaking point gains stacks much faster

first off, let's compare it to serpent mask, the closest thing to a replacement:

the serpent mask:
-gives less weapon power (+150 -> +85)
-gives lifesteal (0% -> 10%)
-has a passive (none -> your next 600-1200 (level 1-12) points of weapon damage to enemy heroes has +25% lifesteal, recharges over 40 seconds)
-costs less (3100 -> 2800)

is it worth it?

to start it off, I think damage is equal to healing, its just as good to kill your enemy much faster than to outlast him in my eyes. with the serpent mask you would lose (150 - 85) 65 weapon power. as I explained earlier, I will compare that 65 weapon power to 65 healing. for the serpent mask to be better I would need to get 65 healing from it with each hit. with that passive it is really hard to calculate it, but I will try to get a very close guess:

first, the amount of damage you would be doing in team fights, I have guessed how much health a full team would have on lvl 12:

~1400 laner
~1600 warrior
~1700 tank/support
~1700 health items
total ~6400 health

because breaking point gets stronger very fast, I would think (if you survive long enough) you would do about half of all damage in a teamfight, so if you survive a complete fight, you would be doing about 3200 damage:

first 1200 damage: 10% lifesteal + 25% lifesteal from passive = 35% lifesteal = 1200 : 100 x 35 = 420 healing
other 2000 damage: 10% lifesteal = 2000 : 100 x 10 = 200 healing
total damage: 3200
total healing: 620
620 : 3200 x 100 = 19.4% lifesteal over the course of a whole teamfight

now as to how much healing that would be on every basic attack, I would have to calculate how much weapon power damage Krul does with all items on lvl 12:

with sorrowblade:
base weapon power: 139 weapon power
sorrowblade: 150 weapon power
breaking point: 55 weapon power
bonesaw: 15 weapon power
total: 359 weapon power

with serpent mask:
base weapon power: 139 weapon power
serpent mask: 85 weapon power
breaking point: 55 weapon power
bonesaw: 15 weapon power
total: 294 weapon power
lifesteal: 19.4% lifesteal
294 : 100 x 19.4 = 57 healing per hit

so or 65 extra damage (sorrowblade) or 57 extra healing (serpent mask) per basic attack. I think sorrowblade is better, not only is it (in my eyes) better, it also charges up your breaking point faster.

another possible comparison would be shatterglass, the crystal power alternative:

the shatterglass:
-gives crystal power instead of weapon power (+150 -> +150)
-costs less (3100 -> 3000)

I am not gonna go deeper into this, because I already talked about it alot in the section above (How effective is weapon and crystal power?)

next, breaking point

passive: gain 10 weapon power for every 125 weapon damage dealt to enemy heroes (+5 damage needed for each stack thereafter). 25 stacks max. decays 2 stacks per second after you’ve stopped stacking for 2 seconds
+35% attack speed
+55 weapon power

good for 3 things:
-you get your weakness stacks on your enemy at a higher rate
-your breaking point gains stacks faster
-fights get easier if they last longer, breaking point deals more damage based on an amount of damage you've dealt

the only item that looks even a bit like it, would be broken myth:

the broken myth:
-has a different passive (gain 10 weapon power for every 125 weapon damage dealt to enemy heroes (+5 damage needed for each stack thereafter). 25 stacks max -> passive: amplify all crystal power damage by 7%per second when in combat with enemy heroes (5 stacks max))
-has no attack speed (+35% -> +0%)
-has crystal power instead of weapon power (55 -> 70)
-has shield pierce (+0% -> +10%)
-costs more (2600 -> 3100)

just like the shatterglass, I won't get any further into this item simply because it would require a crystal power build and wouldn't fit into this deck

the bonesaw

on hit: your basic attacks shred 6% of the target's armor for 3 seconds. max 8 stacks
+15 weapon power
+50% attack speed

good for 3 things:
-you get your weakness stacks on your enemy at a higher rate
-your breaking point gains stacks faster
-the longer you fight, the less the enemies' armor effects you, when you have hit 8 basic attacks you reach max stacks, 48% armor piercing

the closest thing would be its counterpart, the broken myth:

the broken myth:
-has a different effect (on hit: shred 6% armor (8 stacks max) -> passive: amplify all crystal power damage by 7% when in combat with enemy heroes (5 stacks max))
-has no attack speed (+50% -> +0%)
-has crystal power instead of weapon power (15 -> 70)
-has shield pierce (+0% -> +10%)
-costs more (2700 -> 3100)

the journey boots

(in the case of the tank build it's war treads. that is because it provides more health)

passive: +0.6 move speed (Does not stack with other boots)
passive: travel
activate: Sprint for 2 seconds (60s cooldown). damaging heroes instantly sets the cooldown to 12 seconds if it is above it
+250 health

good for 2 things:
-increases your speed, so you can stay close to your enemies much easier
-increases your health, making it harder for the enemy to kill you

you can replace the journey boots with any other type of boots, but, especially for Krul, you need to stick to your enemies, and the best way to do that is with the fastest boots in the game

the aegis

activate: reflex block (35s cooldown)
+125 shield
+30 armor
+200 health

good for 4 things:
-increases your health, making it harder for the enemy to kill you
-increases shield, making it very hard for enemies that use a crystal power build to kill you
-increases armor, making it harder for enemies that use a weapon power build to kill you
-gives you a reflex block so you can protect yourself against stuns

looks alot like fountain of renewal:

the fountain of renewal:
-has a different passive (none -> regenerates 2.5% of your missing health per second whenever you are out of combat with enemy heroes for 5 seconds)
-has a different activate ability (reflex block -> heals you and nearby allies for 2 health for each % missing health per second for 3 seconds)
-activate ability has a higher cooldown (35 seconds -> 60 seconds)
-has the same amount of health (200 -> 200)
-has less shield (125 -> 75)
-has the same amount of armor (30 -> 30)
-costs more (2250 -> 2300)

the metal jacket

+170 armor
+35 shield

good for 2 things:
-increases shield, making it harder for enemies that use a crystal power build to kill you
-increases armor, making it very hard for enemies that use a weapon power build to kill you

looks alot like atlas pauldron:

atlas pauldron:
-has less armor (170 -> 85)
-has the same amount of shield (35 -> 35)
-has an activate ability (none -> reduces attack speed of nearby enemies by 65% for 5 seconds in a 4-meter range. does not reduce below the base attack speed animation (15s cooldown))
-costs less (2100 -> 1900)

the shiversteel

(this is only in my tank build)

activate: for the next 4 (6 if you are melee) seconds, your basic attacks slow the target by 40% for 1.2 seconds (18s cooldown)
+500 health

good for 2 things:
-increases your health, making it harder for the enemy to kill you
-when activated it slows enemies when you attack them. makes it much easier to stay close to them

there is really not an item you could, or should replace this with. it just fits Krul's playstyle to much

what to buy in different situations?

both builds use the items aegis and metal jacket. this is for the most common situation in which your enemy would have 1 weapon power character, 1 crystal power character and a tank/support character. this is however not always the case, so I will give you some choices for different situations:

against 2 or more heavy crystal power enemies:

1. aegis + fountain of renewal, I use this one the most because it gives you 200 extra shield total and 2 strong activate abilities

2. aegis + aegis, I don't recommend it, but it provides the most shield out of all options, 250 shield total. the activate ability does not stack, if you use 1 of the 2 aegises the other one will also go on cooldown

3. aegis + crucible, this one is pretty good when there are 2 heavy crystal power enemies and 1 heavy weapon power enemy because health items counter both crystal and weapon, but not as good as armor and shield items do

4. (only for assassin build) aegis + shiversteel, this one is good for the same reason the aegis + crucible is, but this one is probably better for the assassin build because the shiversteel sacrifices 100 extra health for a slow that can help you heal and is probably more useful than a second reflex block

against 2 or more heavy weapon power enemies:

1. metal jacket + atlas pauldron, I use this one the most because both items together provide 255 armor. with all that armor comes an attack speed slow that you can use to stop some of that weapon power burst damage and give you a chance to build up your healing stacks

2. metal jacket + metal jacket, if you have no use for attack-speed-slowing activate abilities, this is the combo for you, 340 armor, no weapon power character is gonna get through that

3. metal jacket + crucible, this one is pretty good when there are 2 heavy weapon power enemies and 1 heavy crystal power enemy because health items counter both crystal and weapon, but not as good as armor and shield items do

4. (only for assassin build) metal jacket + shiversteel, this one is good for the same reason the metal jacket + crucible is, but this one is probably better for the assassin build because the shiversteel sacrifices 100 extra health for a slow that can help you heal

NEVER go atlas pauldron without a metal jacket, atlas pauldron's armor is just to low and won't protect you enough. even with the attack speed slow, after the effect wares off you'll die faster than you can heal because the amount of armor on atlas pauldron is to low to protect against 2 (or more) heavy weapon power characters

thank you for reading through my 'ALL ABOUT KRUL' guide. I hope my guide helped you with playing Krul and improving your build. if you haven't played Krul yet, he's very hard to play, but when you practice enough he's really fun.

Thanks for reading my guide and I hope you give Krul a try.