Regeltext

When your opponent would Normal or Special Summon a monster(s) while you control "Atlantis, City of the Sea Dragon": Negate the Summon, and if you do, destroy that monster(s), then if you control a WATER Link Monster, you can destroy all non-WATER monsters on the field. You can banish this card from your GY and send 1 face-up "Umi" you control to the GY, then target 1 monster your opponent controls; send it to the GY. You can only use 1 "Daedalus Maelstrom" effect per turn, and only once that turn.