You can send 1 face-up "Umi" you control to the GY; destroy all other cards on the field.
While this card is on the field: The turn player can Fusion Summon 1 Fusion Monster from their Extra Deck, by banishing Fusion Materials listed on it from their hand or field.
King of the Swamp
ATK 500DEF 1100
This card can be used as a substitute for any 1 Fusion Material whose name is specifically listed on the Fusion Monster Card, but the other Fusion Material(s) must be correct. You can discard this card to the Graveyard; add 1 "Polymerization" from your Deck to your hand.