Fateful Moment

Whenever a player casts a non-creature spell you may pay {u}{u} or sacrifice a Spirit. If you do, untap Fateful Moment and it becomes a 4/4 Dragon Spirit Construct creature with Flying and "Sacrifice a Spirit: Regenerate Fateful Moment."
Fortified by centuries of mystical wards, the greatest of the dragon lords could not be truly destroyed by the Annihilation Wave. Their bodies remain preserved at the moment of death, briefly springing to life in the presence of magic.