Artifact Creature â Construct
Whenever Bomat Courier attacks, exile the top card of your library face down. (You can't look at it.)
, Discard your hand, Sacrifice Bomat Courier: Put all cards exiled with Bomat Courier into their owners' hands.
Craig J Spearing INTERVIEW
You can pay the cost of â€œdiscard your handâ€ even if your hand contains zero cards.
If Bomat Courier leaves the battlefield before you activate its last ability, any cards exiled by its triggered ability remain exiled face down for the rest of the game. If you somehow return the same Bomat Courier card to the battlefield, it will be a different object with no connection to those face-down cards.
Each Bomat Courier you control has its own cache of cards. Bomat Courierâ€™s last ability only puts those cards into your hand, not those of any other Bomat Courier.