Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
I've played Cho for a very long time, and I found this build the best. Many times Cho users are in a dilemma because they have to choose between TANK and AP. This build gives a balance for the two and maximizes both the best it can.
Especially in a team that has more than one tank or is in need of more AP damage output, this build will get you the win.
Keys to this build is AP DAMAGE, FAST CD, and TANK. This build gives a balance of the three to maximize damage while maintaining Cho's tanking ability.
Magic pens and CD reductions are a must, and you can never go wrong with ~100 health quints. As for dodge, they can be reconsidered but I prefer them for any of my champs.