You're right about the vulnerability, but I personally let my team mates engage which gives me a chance to carefully pick out an enemy or 2 with suppressing fire. Then I go in with mad canon already loaded and finally pick off any fleeiers with Roadie Run. Also random tip: load mad canon at base so it effectively costs you no energy. Its a different play style and I see the merit of your guide. Pretty awesome.

@CrystalSawce thanks for your continued feedback, I appreciate it and will check out your build.
What you said is true but will make you extremely vulnerable to stuns and focusing. This build does not begin with Shatterglass and is not going to have the stacked CP power you mentioned. Additionally, Aftershock applies to mainly his Roadie Run and only the first shot of his ult.
While your build relies on the focus fire of SAW ult, this one is reliant on his A as a one shotting ability.

I understand the situational advantages of that but overall shear crystal power will make you more effective against non human elements (such as the kraken, the turrets and the enemy crystal) and overall. In my experience in the game I find that when enemies start building D they become less powerful late game and unless they are tanked up filling multiple slots with D (easily avoidable characters) mad canon shells with 5 stacked shatterglasses will end any team fight. Ive posted a build you should try it out.

Good question @CrystalSawce
If you build 2 Shatterglasses, which is a flat crystal boost, the enemy's shield value becomes more valuable. Obviously, late game shield values are much higher than early game due to leveling and builds. And since Shatterglass will be built towards the late game in this build, you'll be providing the most value for the enemy shield values (the higher the incoming CP damage, the more effective x shield value is).
So to maximize your potential late game damage, you should spend in shield pierce along with a little crystal power from Frostburn and make the most of it.
On top of that, most players will recognize your Crystal Saw and build shield. If you are in the middle of 2 Shatterglasses, your effectiveness will be reduced entirely, and you'll have to essentially sell and re-spec into shield pierce, wasting gold.

Think of Broken Myth v. Shatterglass as Skaarf's passive buff in the latest patch (check the patch notes) which gives him more bang for each crystal damage but lessens his early game deadliness wih less damage. The reason this is a buff is because his passive actually does more damage than before in the late game due to the higher shield values being bypassed by shield pierce.

Stacking shaterglass works... Why isnt it effective?