This is my AP Master Yi build. Since his Q and W is useful I suggest maxing them early as possible then Get his R and E. This would make his Q do a ****load of damage. It would make him alost impossible to kill if you know how to use him. Now that his W will heal all his health at this point you are Safe. If you want to get coo ldown reduction get blue buff since you could probably 2 hit it.