Pros: Is great when facing a more damage based build enemy.
Doesn't necessarily sacrifice other ability outputs.
Is a basic build that is great for newbies on Zeratul.

Cons: Sacrifices a lot of damage potential and won't do much against tanks.
Not good for laning.

Others: It won't matter what your Heroic is.

Pros: Is great when facing a tankier or sustainable team.
Greatly increases damage potential if playing Zeratul right.
Is great when in sync with other abilities.

Cons: Doesn't do great for newbies on Zeratul, or for those who tend to be passive.
Can leave Zeratul vulnerable to stuns, slows, roots, etc.
Isn't great when playing with an all damage team.

Other: Focused attack for tier 2(level 4) can increase damage potential, but decrease survivability rate.
Follow Through is also a good choice for a tier 3(level 7) talent.
Assassin's Blade is also a good choice for a tier 5(level 13) talent.
Nerazim Fury is an ok choice, but I don't prefer it whereas shadow assault can leave you vulnerable, especially when roaming, as a tier 7(level 20) talent.

READ BEFORE USING THE BUILD PLEASE.
The Off-Tank build for Zeratul only increases his survivability, and doesn't bring him to his full potential as an assassin. Zeratul can still be easily killed with this and barely allows him to over extend. The intention of this build is to provide players with some good talents that can be used if you're having troubles surviving fights with Zeratul against other heroes. I don't recommend using all the same talents in matches, whereas it makes Zeratul extremely vulnerable and doesn't give as much as it takes.