Carnivorous Cultivator // Enroot

If a prepare spell with one or more targets has no legal targets when it tries to resolve, it won't resolve and none of its effects will happen. Since the spell was cast, the associated permanent will still not be prepared.

If a prepared creature loses all abilities, it won't stop being prepared, and nothing will happen to its alternative characteristics or to the copy of its prepare spell in exile.

Creating a copy of a creature's prepare spell in exile ignores copy exceptions applied to that creature that would affect the copiable values of that spell. For example, say a player casts Croaking Counterpart (a sorcery that says "Create a token that's a copy of target non-Frog creature, except it's a 1/1 green Frog") targeting Diviner of Victory. The token copy of Diviner of Victory will enter prepared as a 1/1 green Frog creature, but the copy of Unwind History in exile will still be a blue sorcery. The copy of Unwind History won't be green, a creature, or a Frog, and it won't have power or toughness.