Passive: Deadly Venom
Twitch's passive stacks and does true damage to your enemies. Very helpful for poking enemies and is used with expunge to deal burst damage.
Allows Twitch to position and gain attack speed after breaking invisibility. You can use this ability to scout for enemies and escape from harm although it takes 3 seconds to go invis.
W: Venom Cask
This is an aoe skill applying 2 stacks of poison to the enemy. You should use this skill when you go invisible to surprise them and add 2 stacks for expunge.
Twitch's most deadly skill which can also be used on multiple enemies. Expunge should be used when you have 6 stacks on your enemy and see the x above their head. Also a good skill for clearing waves and harassing.
R: Spray and Pray
Twitch's ultimate increases his damage and range and also allows him to pierce through multiple enemies. With the combination of your expunge, this makes twitch very strong in team fights especially since he can position himself before the fight begins. One drawback with his ultimate is that you can miss the ability because it doesn't lock onto the target.