When Contagion Engine enters the battlefield, put a -1/-1 counter on each creature target player controls. {4}, {T}: Proliferate, then proliferate again. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)

Equipped creature gets +1/+1 for each counter on it. Equipped permanent isn't a planeswalker and is a creature in addition to its other types. (Loyalty abilities can still be activated.) Equip planeswalker {1} Equip {3}

At the beginning of each player's upkeep, that player puts a flood counter on target non-Island land they control of their choice. That land is an Island for as long as it has a flood counter on it. At the beginning of each end step, if all lands on the battlefield are Islands, remove all flood counters from them.

This spell can't be countered. Green spells you control can't be countered. {4}{G}{G}: Until end of turn, each Elf creature you control has base power and toughness 5/5 and becomes a Dinosaur in addition to its other creature types.

Arixmethes, Slumbering Isle enters the battlefield tapped with five slumber counters on it. As long as Arixmethes has a slumber counter on it, it's a land. (It's not a creature.) Whenever you cast a spell, you may remove a slumber counter from Arixmethes. {T}: Add {G}{U}.

Flying Whenever Aven Courier attacks, choose a counter on a permanent you control. Put a counter of that kind on target permanent you control if it doesn't have a counter of that kind on it.

Partner with Owen Grady, Raptor Trainer (When this creature enters the battlefield, target player may put Owen into their hand from their library, then shuffle.) For each kind of counter on Blue, Loyal Raptor, each other Dinosaur you control enters the battlefield with a counter of that kind on it.

Spells your opponents cast that target Charix, the Raging Isle cost {2} more to cast. {3}: Charix gets +X/-X until end of turn, where X is the number of Islands you control.

Flying At the beginning of your upkeep, sacrifice Chisei, Heart of Oceans unless you remove a counter from a permanent you control.

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Whenever Cold-Eyed Selkie deals combat damage to a player, you may draw that many cards.

Whenever an opponent shuffles their library, you may put a +1/+1 counter on Cosi's Trickster.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.) Creatures you control have "Whenever one or more counters are put on this creature for the first time each turn, draw a card."

When Deepglow Skate enters the battlefield, double the number of each kind of counter on any number of target permanents.

Whenever another Merfolk enters the battlefield under your control, put a +1/+1 counter on target Merfolk you control.

{T}: Add {C}. {T}: Add one mana of any color. Spend this mana only to cast a legendary spell, and that spell can't be countered.

Ferropede can't be blocked. Whenever Ferropede deals combat damage to a player, you may remove a counter from target permanent.

Floodchaser enters the battlefield with six +1/+1 counters on it. Floodchaser can't attack unless defending player controls an Island. {U}, Remove a +1/+1 counter from Floodchaser: Target land becomes an Island until end of turn.

{2}{G/U}, {Q}: Double the number of each kind of counter on target permanent. ({Q} is the untap symbol.)

Kumena's Speaker gets +1/+1 as long as you control another Merfolk or an Island.

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

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

When you control no Islands, sacrifice Seasinger. You may choose not to untap Seasinger during your untap step. {T}: Gain control of target creature whose controller controls an Island for as long as you control Seasinger and Seasinger remains tapped.

Serpent of the Endless Sea's power and toughness are each equal to the number of Islands you control. Serpent of the Endless Sea can't attack unless defending player controls an Island.

Affinity for Islands (This spell costs {1} less to cast for each Island you control.) Flying

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Merfolk spells and Wizard spells you cast cost {1} less to cast.

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) All lands are Islands in addition to their other types. Creatures without flying or islandwalk can't attack.

Flying If you would proliferate, proliferate twice instead. {1}{U/P}{U/P}, Remove three counters from among other artifacts, creatures, and planeswalkers you control: Put an indestructible counter on Tekuthal, Inquiry Dominus. ({U/P} can be paid with either {U} or 2 life.)

Flying Tempest Djinn gets +1/+0 for each basic Island you control.

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Whenever Thada Adel, Acquisitor deals combat damage to a player, search that player's library for an artifact card and exile it. Then that player shuffles. Until end of turn, you may play that card.

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Water Always Wins — Whenever The Flood of Mars attacks, put a flood counter on another target creature or land. If it's a creature, it becomes a copy of The Flood of Mars. If it's a land, it becomes an Island in addition to its other types.

Tidewalker enters the battlefield with a time counter on it for each Island you control. Vanishing (At the beginning of your upkeep, remove a time counter from this creature. When the last is removed, sacrifice it.) Tidewalker's power and toughness are each equal to the number of time counters on it.

At the beginning of your precombat main phase, remove all flood counters from Bounty of the Luxa. If no counters were removed this way, put a flood counter on Bounty of the Luxa and draw a card. Otherwise, add {C}{G}{U}.

At the beginning of each of your main phases, if you haven't added mana with this ability this turn, you may add X mana of any one color, where X is the number of Islands target opponent controls.

Islands don't untap during their controllers' untap steps.

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead. If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

As Roots of Life enters the battlefield, choose Island or Swamp. Whenever a land of the chosen type an opponent controls becomes tapped, you gain 1 life.

You may return an Island you control to its owner's hand rather than pay this spell's mana cost. Counter target spell unless its controller pays {1}.

You may return two Islands you control to their owner's hand rather than pay this spell's mana cost. Tap all creatures.

You may return two Islands you control to their owner's hand rather than pay this spell's mana cost. Draw two cards.

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Hinterland Harbor enters the battlefield tapped unless you control a Forest or an Island. {T}: Add {G} or {U}.

{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

Put a flood counter on target land. That land is an Island in addition to its other types for as long as it has a flood counter on it. If you control a Merfolk, draw a card.

Return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control. Foretell {1}{U}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Destroy all Islands.