When Oubliette enters, target creature phases out until Oubliette leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)
Select a creature in play when Oubliette is cast. That creature is considered out of play as long as Oubliette is in play. Hence the creature cannot be the target of spells and cannot receive damage, use special powers, attack, or defend. All counters and enchantments on the creature remain but are also out of play. If Oubliette is removed, creature returns to play tapped.
--This card has no flavor text --