The Kingsguard

When the only other players are The King, their
teammates and your teammates, reveal The
Kingsguard and you all win the game. When
there is no King, you lose the game.
If combat damage dealt from unblocked attacking
creatures could cause a King to lose the game, you
may turn The Kingsguard face up. If you do,
prevent all combat damage that would be dealt
this turn.