Otpikis, Storm Swallower

{x}{u}{u}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it an it becomes monstrous.)
When Otpikis, Storm Swallower becomes monstrous, return up to X target creatures to their owners' hands where X is the number of +1/+1 counters on Otpikis, Storm Swallower.