The League of Legends is officially welcoming Mac-wielding summoners into its halls with an open beta for a Mac client. The client connects to the same services as the PC version, with all the same features. You can find it here--keep in mind it is a beta, so some bugs are to be expected.
Mac support has been a pressing issue for Riot Games for years. Up until now, Apple-aficionados have had to rely on third-party emulation to access one of the most-played computer games in the world.
Dr. Mundo is apparently a bit of a Macolyte himself.