msem-instigator

Other Merfolk you control get +1/+1.
When Olantin Pearlreader enters, scry 2. Then draw a card if you control two or more other Merfolk.

When Old Salt enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Flash
Flying

{3}{U}, Exile a card from your graveyard: Omen Serpent can't be blocked this turn.

Colossal 3—{5}{U} (You may cast this for its colossal cost to have it enter with three +1/+1 counters; or pay {5}{U} as a sorcery: Put three +1/+1 counters on it if it has none.)
When Omendiver's colossal ability puts one or more counters on it, scry 3.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
Spells you cast from zones other than your hand cost {3} less to cast.

Look at the top two cards of your library. Put one of them into your hand and the rest into your graveyard.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

Whenever you draw a card, put a foreshadow counter on Ominous Seas.
Remove eight foreshadow counters from Ominous Seas: Create an 8/8 blue Kraken creature token.
Cycling {2} ({2}, Discard this card: Draw a card.)

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.

I, II — Put your choice of a flying or hexproof counter on target creature you control.
III — Creatures you control with counters on them can't be blocked this turn unless defending player pays {3} and spells that target those creatures cost an additional {3} to cast until your next turn.
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This spell costs {1}{U} less to cast if it targets a red or green spell.
Counter target spell.
Draw a card.

Reprise {3}{U} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)
Create a Treasure token. You draw cards equal to the number of tokens created by this spell.

Enchant creature
Enchanted creature gets +2/+2 and has flying.

Spells your opponents cast that target Onigori, Ema's Shield cost {2} more to cast.
Whenever Onigori deals combat damage to a player, that player can't untap more than two permanents during their next untap step.

Flying
At the beginning of your end step, up to one other target creature you control voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever a creature you control phases in, you may have it become a copy of target creature you control until end of turn.

Exile two target permanents you control, then return them to the battlefield under your control.

Flash
Whenever Operative POSH attacks or you cast a green or red spell, exile up to one target nontoken permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Once each turn, you may pay {U} rather than pay the mana cost for a blue spell you cast.

Scry 1.
Draw a card.

Whenever Optimistic Chronicler deals damage to a player or noncreature permanent, surveil 1, then draw a card.

Whenever you cast your first instant or sorcery spell each turn, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

When Oracle Crab enters, scry 2. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)

When Oracle of Edicts enters, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Whenever an Aura you control enters, scry 1.

Search your library for up to six cards and exile them face down. Shuffle, then draw a card.

As an additional cost to cast this spell, you may tap any number of untapped tokens you control. This spell costs {1} less to cast for each token tapped this way.
Whenever Organic Dreadnought enters or attacks, tap target permanent an opponent controls. That permanent doesn't untap during its controller's next untap step.