Devoted Crop-Mate

If a creature has a targeted triggered ability that triggers when you exert it, you can exert it even if there isn't a legal target for that triggered ability.

If the creature returned to the battlefield has any abilities that trigger when creatures attack or when you exert creatures, those abilities won't trigger.

If the mana cost of a card in your graveyard includes X, X is considered to be 0.

You can't exert a creature unless an effect allows you to do so. Similar effects that "tap and freeze" a creature (such as that of Decision Paralysis) don't exert that creature.

If an exerted creature is already untapped during your next untap step (most likely because it had vigilance or an effect untapped it), exert's effect preventing it from untapping expires without having done anything.