Reverent Mantra 
Instant
You may exile a white card from your hand rather than pay this spell's mana cost. Choose a color. All creatures gain protection from the chosen color until end of turn.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL