The Q is the powerhouse of the Cho'Gath. If you can land this simple AOE you can do massive damage, especially late game. It's range is also amazing and most top-laners are melee so you can see where this is going.

The W is extremely useful against people like Fiora who try to poke, or any champion slightly out of reach from your basic attack. I recommend using this after slowing them with Q or E to prevent self-defence.

I only use Cho'Gath's E to farm quicker, or damage enemies while low on mana, however it is also possible to use it to slow enemy champions instead of Q.

Only use when health bar is surrounded by red.

Poke with Q early game, ensure you have teleport advantage at all times and lane correctly (farm according to minion advantage). Late game, button mash. Cho'gath is easy to play and if you play early game correctly, you can bully their entire team in late game.