Calamity-Class Charybdis (TSK/S82-E064 C) [That Time I Got Reincarnated as a Slime Vol.2]

Put this card into your memory. [AUTO] Memory At the beginning of your main phase, if this card is in your memory, choose 1 card in your waiting room, put it face down into your memory, if your memory has 3 or more face down cards, choose 3 face down cards in your memory, and put them into your waiting room. If you put 3 cards into your waiting room, deal 3 damage to your opponent, and put this card into your waiting room. (Damage may be canceled) [AUTO] Memory [(2)] At the beginning of your opponent's main phase, if this card is in your memory, your opponent may pay the cost. If they do, choose 1 face down card in your memory, and put it into your waiting room.