What is mai-coh?

Answer 1

According to wererat.net, mai-coh is the Navajo Indians' skinwalkers. See http://wererat.net/werewhere.htm

Answer 2

It's possible that you are referring to the game "minecraft." It is a popular sandbox video game where players can explore, create, and survive in a blocky, pixelated world. If you have a different context for "mai-coh," please provide more information for clarification.