The Crystal Infusion is a consumable that adds 72 Crystal power and 35% CD at lv12 for 3 minutes, which means by selling one of your items, and consuming this item and buy the original item back, you would spend (Sold item original price)/2 + 500 total, but gaining three minutes of huge advantage.

Krul is really a tough opponent for Koshka, since his smite stacks not only grant him life steal, and can weaken the target's Crystal Power, which is quite devastating for Koshka. My solution for this is to dish out as much damage as I can before he get four smite stacks on me, then I run like mad. If Krul choose to detonate the stacks, I would probably not die right away, which gives me opportunity to turn back and fight him on again. Or I can just run until the stacks expires. Note: Krul's...

Just hope the enemy Catherine and Glaive are newbies too lol

I have explained where to use them in way behind, the third-to-last chapter. Maybe I did not do a good job explaining it though. You can just consider integrating it into this build in order to fit your own play style.

WHAT? Have I been on this spotlight thingy? Well never thought this could happen... Thanks for the support anyway, hehe Hope it helps.