No exile is minor for the midrange and control decks and so overall you just always put a Searing Spear and an Incediary Flow into a drafting cube long before you entertain this otherwise fantastic spell
Because Augment and host cards are not plentiful, I could see this as just a bad deck, and not the cool, Selesnya Mistform Ultimus that comes with it
This ultimately creates a very slippery slope that could lead to Wizards printing contemporary celebrities in major sets
Second, once an Aura with bestow is on the battlefield, if the enchanted creature leaves the battlefield, the Aura stops being an Aura, it loses enchant creature, it becomes an enchantment creature, and it stays on the battlefield
Nonetheless, being able to tutor a card like Yawgmoths Will in Storm or Tinker in an Artifact-centric Vintage deck is extremely strong