msem-instigator

Concord — When Riptide Mystic enters the battlefield, if there are four or more card types among permanents you control, you may return target nonland permanent to its owner's hand.

({T}: Add {U} or {R}.)
As Ritzy Parlor enters the battlefield, you may pay {1}. If you don't, Ritzy Parlor enters the battlefield tapped.

{U}, {T}: You may tap or untap another target creature.
Whenever one or more other creatures you control deal combat damage to a player, you may untap Riverchase Diver.

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

({T}: Add {U} or {R}.)
Roaring Cascade enters the battlefield tapped.

Whenever you cast an instant or sorcery spell, reveal the top card of your library. If an instant or sorcery card is revealed this way, draw a card.

At the beginning of each upkeep, choose another permanent with the greatest mana value among permanents. Its controller sacrifices it.

Rosegill Rover can't be blocked.
Whenever Rosegill Rover attacks, you may discard a card. If you do, draw a card.

Ward {2}
{G}{G}{G}, {T}, Exile a creature card from your graveyard: Search your library for up to two creature cards that share a name with the exiled card, reveal them, put them into your hand, then shuffle.

When Rum Guzzler enters the battlefield, forebode, then you lose 1 life. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

({T}: Add {U} or {R}.)
As Ruptured Falls enters the battlefield, you may pay {1}. If you don't, Ruptured Falls enters the battlefield tapped.

({T}: Add {U} or {B}.)
As Ruptured Grotto enters the battlefield, you may pay {1}. If you don't, Ruptured Grotto enters the battlefield tapped.

({T}: Add {G} or {U}.)
As Ruptured Grove enters the battlefield, you may pay {1}. If you don't, Ruptured Grove enters the battlefield tapped.

({T}: Add {W} or {U}.)
As Ruptured Square enters the battlefield, you may pay {1}. If you don't, Ruptured Square enters the battlefield tapped.

Improve {1}{U} ({1}{U}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
At the beginning of your end step, if one or more embattled creatures you controlled dealt damage to a player, you may draw a card. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Rustshell Crustacean gets +1/+1 for each artifact you control.
Whenever Rustshell Crustacean attacks, choose one —
• Search your library for an Equipment card, reveal it, and put it into your hand, then shuffle.
• Create a Treasure token.

When Saddled Scuttleback enters the battlefield, you may search your library for a Crab, Fish, Jellyfish, Kraken, Leviathan, Merfolk, Nautilus, Octopus, Otter, Oyster, Pirate, Seal, Serpent, Shark, Shrimp, Sponge, Squid, Starfish, Trilobite, Turtle, Whale, or Island card, reveal it, put it into your hand, then shuffle.

When Safety Expert enters the battlefield, if you have more life than your starting life total, put a +1/+1 counter on target creature.

Flash
First strike (This creature deals combat damage before creatures without first strike.)

When Salty Swab enters the battlefield, exile the top three cards of your library.
Resolute — You may play cards exiled with Salty Swab as long as Salty Swab's power is greater than its base power.

{7}, {T}, Sacrifice Samaki School: Look at the top four cards of your library. Put two into your hand and the rest on the bottom of your library in any order.

Menace
When Santriza Gang-Boss enters the battlefield, it deals X damage to any target, where X is the number of Pirates and/or Rogues you control.

({T}: Add {U}.)
As Saturated Dunes enters the battlefield, you may pay 1 life. If you don't, Saturated Dunes enters the battlefield tapped.

Whenever Scaleblight Cutthroat attacks, each opponent loses life equal to its power.
{4}{B}{B}: Scaleblight Cutthroat gets +3/+3 until end of turn.

Schoolmaster gets +1/+1 for each other Merfolk you control.
When Schoolmaster enters the battlefield, create a 1/1 white Merfolk creature token.