Oubliette
Enchantment
When this enchantment enters, target creature phases out until this enchantment 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.)
Illustrated by
The List#2XM-100UncommonEnglishLegality
Rulings
If Oubliette leaves the battlefield before its first ability has resolved, its second ability will trigger and do nothing. Then its first ability will resolve and exile the targeted creature forever.
If the targeted creature is a token, it will cease to exist after being exiled. Any Auras that were attached to it will remain exiled forever.
If the exiled card is returned to the battlefield and, for some reason, it now can’t be enchanted by an Aura that was also exiled by Oubliette, that Aura will remain exiled.