Crystalline Nautilus
Enchantment Creature — Nautilus
When this permanent becomes the target of a spell or ability, sacrifice it.
Enchanted creature gets +4/+4 and has "When this creature becomes the target of a spell or ability, sacrifice it."
Legal in
Pioneer, Modern, Legacy, Vintage, Commander
Rulings (9)
Similarly, if you cast an Aura spell with bestow targeting a creature controlled by another player, and that creature is an illegal target when the spell tries to resolve, it will finish resolving as an enchantment creature spell. It will enter the battlefield under your control.
2014-04-26
If a permanent with bestow enters the battlefield by any method other than being cast, it will be an enchantment creature. You can't choose to pay the bestow cost and have it become an Aura.
2014-04-26
Unlike other Aura spells, an Aura spell with bestow isn't countered if its target is illegal as it begins to resolve. Rather, the effect making it an Aura spell ends, it loses enchant creature, it returns to being an enchantment creature spell, and it resolves and enters the battlefield as an enchantment creature.
2014-04-26
Unlike other Auras, an Aura with bestow isn't put into its owner's graveyard if it becomes unattached. Rather, the effect making it an Aura ends, it loses enchant creature, and it remains on the battlefield as an enchantment creature. It can attack (and its abilities can be activated, if it has any) on the turn it becomes unattached if it's been under your control continuously, even as an Aura, since your most recent turn began.
2014-04-26