Devoted Crop-Mate

18/04/17

All attackers are chosen at once. You can’t attack with Devoted Crop-Mate, return a creature card to the battlefield, and then attack with that creature.

18/04/17

All cards in the Amonkhet set that let you exert a creature let you do so as you declare it as an attacking creature, as do some of the cards in the Hour of Devastation set. You can’t do so later in combat, and creatures put onto the battlefield attacking can’t be exerted. Any abilities that trigger on exerting an attacking creature will resolve before blockers are declared.

18/04/17

If you gain control of another player’s creature until end of turn and exert it, it will untap during that player’s untap step.

18/04/17

The converted mana cost of a card in your graveyard is determined solely by the mana symbols printed in its upper right corner. The converted mana cost is the total amount of mana in that cost, regardless of color. For example, a card with mana cost has converted mana cost 3.

18/04/17

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.