Floating Shield 
Enchantment — Aura
Enchant creature As this Aura enters, choose a color. Enchanted creature has protection from the chosen color. This effect doesn't remove this Aura. Sacrifice this Aura: Target creature gains protection from the chosen color until end of turn.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL