During a draft match, the opponent used All-Fates Stalker to exile my Mouth of the Storm creature. They entered combat and attacked with Mm'mmenon, the Right Hand. I used Dubious Delicacy on All-Fates Stalker with the intent to regain possession of Mouth of the Storm and block. Mouth of the Storm returned onto the opponent's side of the field under their control. I lost the match because they gained a free 6/6 flier when I used my removal spell.