In MTG, I played a Driftgloom Coyote and exiled a nontoken creature (Lilysplash Mentor) that my opponent controlled. Next turn, my opponent plays Sugar Coat on the coyote, turning it into a food:
Enchant creature or Food
Enchanted permanent is a colorless Food artifact with "2, Tap, Sacrifice this artifact: You gain 3 life" and loses all other card types and abilities.
What happens if I sacrifice the food for 3 life? Does the Lilysplash Mentor return to the battlefield or not?
Yes, the creature you exiled (Lilysplash Mentor) returns to the battlefield. Driftgloom Coyote's ability is a continuous effect that lasts only while it's on the battlefield (emphasis mine)
When Driftgloom Coyote enters, exile target creature an opponent controls until Driftgloom Coyote leaves the battlefield.
Regardless of how it leaves the battlefield (including being turned into a food and being sacrificed), it will return the card it exiled as soon as it leaves play (without using the stack).
610.3. Some one-shot effects cause an object to change zones “until” a specified event occurs. A second one-shot effect is created immediately after the specified event. This second one-shot effect returns the object to its previous zone.
Because the Driftgloom Coyote's effect has already happened, removing its abilities doesn't change the condition for the one-shot effect's "until" clause, which is only based on that permanent leaving the battlefield (by any means).
