msem-instigator

When Press-Gang Recruiter enters the battlefield, create a Treasure token.
{5}, {T}, Sacrifice an artifact: Gain control of target artifact or creature until end of turn. Untap that permanent. It gains haste until end of turn. Activate only as a sorcery.

When Prince Crab enters the battlefield, create a Treasure token and an Idol token. (An artifact with “{T}, Sacrifice this artifact: Add one mana of any color” and an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Flying
Whenever Prismatic Scyphozoa attacks or blocks, target player mills three cards.
When Prismatic Scyphozoa dies, create four 1/1 blue Elemental creature tokens with flying.

Defender
Whenever you cast an enchantment, instant, or sorcery spell, scry 1 if it's the first time this ability has resolved this turn. If it's the second time, Prismscale Piranhas can attack this turn as though it didn't have defender. If it's the third time, whenever Prismscale Piranhas deals combat damage to a player this turn, draw a card.

({T}: Add {G}, {U}, or {R}.)
Pristine Dominion enters the battlefield tapped.

Menace, haste

Flash
When Qililia's Scavenger enters the battlefield, look at the top six cards of your library. You may put a Merfolk card with lesser mana value from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
Other Merfolk you control get +1/+1.

Flash
If a spell or ability would cause an opponent to create a token, instead you create that token and that player creates a 1/1 blue Fish creature token.

As long as you control two or more other Pirates, Ragavan has haste.
Whenever one or more Pirates you control deal combat damage to a player, create a tapped Treasure token.

Revive {3}{G} ({3}{G}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

When Raikai Seafarer enters the battlefield, you may search your library for up to three cards named Raikai Seafarer, reveal them, put them into your hand, then shuffle.

({T}: Add {G} or {U}.)
Rainforest Spring enters the battlefield tapped.

({T}: Add {W} or {U}.)
Rainsculpted Gorge enters the battlefield tapped.
{1}, {T}: Add {W}{W} or {U}{U}.

Art of war — At the beginning of your end step, if Raiun Bay Scourge dealt damage to an opponent this turn, gain control of target artifact or enchantment until Raiun Bay Scourge leaves the battlefield.

Whenever you cast a spell that doesn't share a color with Raloran Adept, you may switch target creature's power and toughness until end of turn.

Deception {2}{U}{U} ({2}{U}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Raloran Insurgent deals combat damage to a player, abound. (You may cast a spell that costs less than this from your hand without paying its mana cost.)

Each Merfolk and Wizard you control has “Whenever this creature attacks, abound.” (To abound, you may cast a spell that costs less than that creature from your hand without paying its mana cost.)

Ravenous Attraction enters the battlefield with a +1/+1 counter on it.
Whenever a creature you control dies, double the number of each kind of counter on Ravenous Attraction.

When Raving Brigand enters the battlefield, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)
Whenever you sacrifice an Omen, target player mills three cards.

Hexproof
Paranoia {1}{U} (You may cast this spell for its paranoia cost when a permanent you control leaves the battlefield.)

Deception {U} ({U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever a Pirate or Rogue you control deals combat damage to a player, rediscover a Pirate or Rogue card. (Look at the top card of your library. You may reveal it and put it into your hand if it's a Pirate or Rogue. Otherwise, put it back or into your graveyard.)

When Recruits of the Demeter enters the battlefield, draw a card if you control another Pirate.

Redgill Corsair gets +1/+0 as long as you control an artifact.
When Redgill Corsair dies, create a Treasure token.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Shimmer (Whenever this creature attacks, create a tapped and attacking token that's a copy of it. Exile the token at the beginning of the next end step.)

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
As long as you control three or more artifacts, Regal Seasnake has vigilance. (Attacking doesn't cause it to tap.)