Mothia's cocoon

Put one of your cards and one of your opponents cards aside and on your next turn, flip a coin,if heads, put your card back on the battle field with a +2/+2 counter on it, and discard your opponents card,if tales , put your opponents card back on the battle field with no counter on it, and discard your card
"It felt good inside the cocoon, but when it got time for mothia to chose, I was frightened."