Velen, Prophet of the Naaru
Horde players will fondly remember the first time they slaughtered Velen in the Draenei's crashed spaceship. He's the leader of the Draenei on Azeroth and he's no pushover in the TCG either! 7 resource cost makes him a mid-late game ally, but that passive benefit that deals free damage and puts extra cards in your hands is amazing. It almost makes me wish I had an Alliance deck. Almost.