Basically, Cho mid is amazing vs the majority of your typical mid champions. You don't really need potions with his passive. I generally use rupture to beat them and clear lane, you just gotta remember to anticipate their moves and give them good lead so when they start to run they find themselves in mid air. Then you strike with a feral scream and its chow time. Before level 6 just auto attack, this is when exhaust and flash come in handy. Feral scream is good for damage but mostly use it to keep them from making any countering move to get away after you rupture them. This ap cho build is still pretty tanky, you get your ap to max out around 400, and your a pretty dominant force in the game. If you don't like getting ks during a team fight i wouldn't recommend using cho, it seems like i accidentally kill a lot of my allies kills with vorpal spikes and iceborn gauntlet doing aoe damage.