This is my first build, so please give me feedback. So Twitch is a very good harasser if you know how to harass.

Pros:

-deal massive damage
-good scout
-great ganking ability
-good at assassining people through expunge

Cons

-very low health
-very vulnerable

I get crit damage marks because if you have all that crit, it can deal massive damage. i take armor seals for the durability, and magic pen glyphs because your expunge can deal more full damage that way, i take armor pen quints so ur attack won't be blocked

You can harass the opponent by using ambush and hitting them multiple times and use expunge. At team fights you should stay at the back and use your ult and melt em. You can start ganking at level 6 with a boots of mobility and a zeal is enough.

I take flash and exhaust. Flash because it can help you escape or catch champions, exhaust because in your early game u have no slow, as well the damage reduction can help you survive.

I get ambush so you can scout first, then expunge and max expunge first because of the damage from faraway then your attack range. I get 1 point in debilitating poison in level 8, or if you like to gank, level 4, for the slow. And get your ult at lvl. 6, 11, and 16.