A concrete practice-tool routine for Cho'Gath, built around its real cooldowns and ability costs.
Whenever Cho'Gath kills a unit, he recovers Health and Mana. The values restored increase with Cho'Gath's level.
Do nothing else for five minutes. The passive is the piece nobody isolates, and it is the only part of the kit that is always available.

Whenever Cho'Gath kills a unit, he recovers Health and Mana. The values restored increase with Cho'Gath's level.
Ruptures the ground at target location, popping enemy units into the air, dealing damage and slowing them.
Cho'Gath unleashes a terrible scream at enemies in a cone, dealing magic damage and Silencing enemies for a few seconds.
Cho'Gath's attacks release deadly spikes, dealing damage and slowing all enemy units in front of him.
Devours an enemy unit, dealing a high amount of true damage. If the target is killed, Cho'Gath grows, gaining maximum Health.
Practice tool lets you reset cooldowns, which is useful for learning a combo and useless for learning a champion. Turn the reset off and cast on the real timings — knowing what an ability's downtime feels like is most of what separates a comfortable champion from a new one.
Cho'Gath is mana-gated, which is the real limit on how often you can contest a wave early.
Unglamorous, and the highest-value five minutes of the routine. Melee champions have completely different tower-farming patterns, and this is where you find out which one you are actually playing.
These are the designers' words, not ours — the tips shipped in the client for Cho'Gath.