The undead domain and wizard school, along side the feats Command Undead, Turn Undead, Undead master (+4 effective levels for Command Undead), and mythic undead master (+8 effective levels of command undead and only one save instead of every turn )
I wouldn't mind adding the Undead focused school (and other focused schools eventually) but I'm not convinced of the actual utility of the whole Command Undead feat chain. You don't fight that many undead in the game.
The undead domain and wizard school, along side the feats Command Undead, Turn Undead, Undead master (+4 effective levels for Command Undead), and mythic undead master (+8 effective levels of command undead and only one save instead of every turn )