Being a Twich player myself i can tell you that he is NOT op
His skills focus on DPS. Oracles and wards will take care of the stealth problem.
Twich has epicly low hp and armor. Take him out as many times as you can early game.
Go in teams, no matter how strong Twich gets he cant win a 2 on 1.(Unless you suck and/or are way lower level than he)
Most people think Twich is best off solo. This is a lie.
Twich absolutely sucks at solo. If an enemy Twich is soloing mid, team up and kill it.
If you see Twich one moment, and then hes gone, you run!
OMG, do you know how many times ive seen people charge in after Twich goes poof?
If Twich is in your lane and hes suddenly gone. You tell your team he's missing!
Teamwork is the key to killing Twich!
Twich, just like every other character in the whole game, gets stronger if you feed.
Dont cry "Twich is Op!" when youre the noob feeding him!