Mortal Obstinacy
Journey into Nyx — common
Enchantment — Aura
Mortal Obstinacy rulings:
2014-04-26: You decide whether to sacrifice Mortal Obstinacy as its triggered ability resolves. If it's not on the battlefield at that time, you can't sacrifice it and destroy the target enchantment.
2014-04-26: If another player gains control of the enchanted creature, Mortal Obstinacy will be put into its owner's graveyard.