Clockwork Droid

• WOTC Official Reminder Textofficial rules
  Scry — Look at the top N cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.

• WWizards of the Coast2023-10-13
  Official Ruling
  You may exert Clockwork Droid only as you attack with it. You can't do so later in combat, and creatures put onto the battlefield attacking can't be exerted. The ability that triggers on exerting it will resolve before blockers are declared.
• WWizards of the Coast2023-10-13
  Official Ruling
  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.
• WWizards of the Coast2023-10-13
  Official Ruling
  You can't exert a creature unless an effect allows you to do so. Similar effects that "tap and freeze" a creature don't exert that creature.
• WWizards of the Coast2023-10-13
  Official Ruling
  If you gain control of another player's creature until end of turn and exert it, and then that player regains control of it, it will untap during that player's untap step.

Rulings via Scryfall