Ambros, the flying Citadel

Ambros, the flying Citadel enters the battlefield tapped.
At the beginning of your untap step, you may tap Ambros, the flying Citadel.
If you do, search your library for a castle card and put it onto the battlefield.
At the beginning of your turn, if you control Ambros, Katsunaya and Maloniz, you win the game.
You can control only one Ambros, the flying Citadel.