The Knight

Loyal Defender - Once per game, flip this card over and
reveal your Role. Lose half your life, until The King's next turn, their life total can’t change, they gain protection from everything, and they can not gain commander damage. All permanents they control phase out. Then choose a player, exile a permanent they control.

— Win Condition: You and The King are the only remaining players, you both win.

"Knighthood does not live off fame, but rather deeds."