Use Feast to feed on mobs. Stuck increase his growth and health. Up to 6 stuck. max 3600 health if feast stuck is full.

The AP is wrong it has to be 6xx not 350. The Rabadon's Deathcap increase ap power and the Archangel's Staff makes the MP into AP.

So you will be a good mage, but you are not a tank remember that. You do have more health and def than other mages, but they have easier skills. Cho'gath's skills are a bit hard to get use to. Especial the Rupture. But all of the skill deal big damage.

Whats good about making cho into ap is that his Q skill is a long range and it deals almost half damage to enemies.

If you pick this build, don't rush to kill and remember you are not a tank but a mage =D

My advise is not to die =D and you will win.

He is also great at soloing lines. I've done that some times, when we get junglers.

If you do solo, stay next to the tower and wait for the enemy to come. If they tower dive use Rupture. If you see they over power you, don't be afraid. Just let them take the tower. If they do take it you will have a smaller distance to run and creeps will gather at the second tower. so while helping defing mid or other line. Creeps gather at your line you come back use a few skills and all are dead and you get a lot of coins and lvl up fast.

But i don't think you will have any problems soloing a line. His skills are so strong that you kill the creeps right at the tower. So the enemy team wont have time to attack you. But do be careful of tryn.