Ability ability = new EnchantAbility(auraTarget.getTargetName());
this.addAbility(ability);
// When enchanted creature dies, target player loses X life and you gain X life, where X is its power.
DynamicValue attachedPower = new AttachedPermanentPowerCount();
ability = new DiesAttachedTriggeredAbility(new LoseLifeTargetEffect(attachedPower), "enchanted creature");
ability.addEffect(new GainLifeEffect(attachedPower));
ability.addTarget(new TargetPlayer());
this.addAbility(ability);
}