Nevinyrral's Disk enters the battlefield tapped. {1}, {T}: Destroy all artifacts, creatures, and enchantments.

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

{T}, Sacrifice Rootwater Diver: Return target artifact card from your graveyard to your hand.

Cycling {2} ({2}, Discard this card: Draw a card.)

{3}, {T}: Search your library for a Merfolk permanent card, put it onto the battlefield, then shuffle.

{T}: Target land becomes an Island until end of turn.

Enchant creature You control enchanted creature.

Enchant enchantment At the beginning of the upkeep of enchanted enchantment's controller, Feedback deals 1 damage to that player.

Sacrifice Seal of Removal: Return target creature to its owner's hand.

Return target permanent to its owner's hand.

Counter target spell.

Return all artifacts target player owns to their hand.

Target player draws two cards.

Counter target spell unless its controller pays {X}. If that player doesn't, they tap all lands with mana abilities they control and lose all unspent mana.

Choose one — • Target player draws a card at the beginning of the next turn's upkeep. • Target creature gains flying until end of turn. • Target creature an opponent controls phases out. (While it's phased out, it's treated as though it doesn't exist. It phases in before its controller untaps during their next untap step.)

({T}: Add {U}.)