Adriana's Valor [Conspiracy: Take the Crown]

Hidden agenda (Start the game with this conspiracy face down in the command zone and secretly choose a card name. You may turn this conspiracy face up any time and reveal that name.)
Whenever a creature you control with the chosen name attacks, you may pay {W}. If you do, that creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)