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Protectrix • Sanctum • Creature • Common • Reap: You may fully heal a creature. If you do, that creature cannot be dealt damage for the remainder of the turn. • Artist: Asep Ariyanto • Card Number: CotA:254
Effects may still attempt to deal damage to a creature that "cannot be dealt damage", but the targeted creature's ability will prevent that damage according to the first step of the Damage section of the Timing Chart.
Source: Timing Chart