msem-instigator

Whenever you draw your second card each turn, put a +1/+1 counter on Youthful Tortoise.
Cycling {2} ({2}, Discard this card: Draw a card.)

At the beginning of each end step, if you drew and/or discarded six or more cards this turn, return Anemothrys, Reefcrown from your graveyard to the battlefield.
Cycling {R}{G} ({R}{G}, Discard this card: Draw a card.)

Pressure {B}{G} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Search your library and/or graveyard for a creature card with mana value 3 or less and put it onto the battlefield. If you searched your library this way, shuffle.

When Coralight Paladin enters, you may search your library for an artifact card, reveal it, then shuffle and put that card on top.
Concord — Whenever Coralight Paladin attacks, if there are four or more card types among permanents you control, Merfolk you control get +1/+1 until end of turn.

Pressure {3}{U}{B} (You may cast this spell for its pressure cost if there are seven or more cards in your graveyard.)
Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
{U}{B}, Reveal Cuxuri Beckoner from your hand: Target player mills two cards.

When Dawson's Warden enters, create a Treasure token.
As long as you control three or more artifacts, Dawson's Warden gets +2/+0 and has first strike.

Menace
Other artifact creatures you control have menace.
{2}{B}{R}: Salvage an artifact or creature card. (Exile one from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

Pressure {3}{U}{B} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Destroy up to one target creature. Return all other nonland permanents to their owners' hands.

When Duchess Odelia VII enters, search your library for a nonland permanent card with mana value 1 or less, reveal it, put it into your hand, then shuffle.

Whenever you cast an artifact or enchantment spell, scry 1, then create a 1/1 white Merfolk creature token.
Whenever you cast a Merfolk spell, look at the top card of your library. If it's an artifact or enchantment card, you may reveal it and put it into your hand.

Whenever two or more creatures you control deal combat damage to a player, you gain 3 life and create a Treasure token. (It's an artifact with “{T}, Sacrifice this permanent: Add one mana of any color.”)
Whenever you sacrifice your second permanent each turn, you draw a card and you lose 1 life.

Flash
Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
When Grim enters, if you sacrificed a permanent this turn, exile target tapped creature.

When Hila Okunos enters, look at the top six cards of your library. You may reveal an Aura or Aurashaper card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Whenever another nontoken Aura or Aurashaper you control enters, create a token that's a copy of it.

Concord — You may cast this spell as though it had flash if there are four or more card types among permanents you control.
When Krill-Clan Guardian enters, it fights up to one other target creature. If that creature would die this turn, return it to its owner's hand instead.

Haste
You may cast sorcery and enchantment spells as though they had flash.
Whenever you cast an enchantment, instant, or sorcery spell, Lightning-Fast Lionfish gets +1/+0 and gains first strike until end of turn.

When Lionfrill Hunter enters or when you cycle it, put X +1/+1 counters on another target creature you control, where X is the number of cards with a cycling ability in your graveyard.
Cycling {3}{R}{G} ({3}{R}{G}, Discard this card: Draw a card.)

Creatures can't attack Lord Rickard Dawson unless their controller pays 2 life or discards a card for each creature they control that's attacking him.
[+1]: Create a tapped Treasure token, then you may pay {1}. If you do, each opponent discards a card.
[+1]: You may sacrifice an artifact. When you do, Lord Rickard Dawson deals 3 damage to any target and you gain 3 life.
[–7]: Each opponent gets an emblem with “At the beginning of your end step, if it's not an extra turn, take an extra turn after this one. Target opponent controls you during that turn.”

At the beginning of combat on your turn, if you cast an enchantment spell, an instant spell, and a sorcery spell this turn, create two 3/3 red Shark enchantment creature tokens. You may have any number of those tokens gain haste. If you do, sacrifice the tokens you chose at end of combat.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Concord — Once each turn, when an opponent casts a spell or activates an ability that targets a Merfolk or enchantment you control, you may counter that spell or ability if there are four or more card types among permanents you control.

Pressure—{4}{U}{B}, Sacrifice two creatures. (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Whenever Oryxyth enters or attacks, create an X/X black Horror creature token, where X is the number of cards in your graveyard.
{U}{B}, Sacrifice another creature: Gain control of target creature with power less than the sacrificed creature's power.

Menace
Discard a card: Target artifact creature you control salvages Rappel Liner. Activate only if Rappel Liner is in your graveyard and only as a sorcery. (Exile this card until that creature leaves the battlefield. When that creature deals combat damage to a player, return a card it salvaged to your hand.)

First strike, trample
Whenever Regal Coralhorn deals combat damage to a player or planeswalker, return target card with a cycling ability from your graveyard to your hand.
Cycling {2} ({2}, Discard this card: Draw a card.)

Spells your opponents cast that target Shoalshine cost an additional {2} to cast.
Concord — {T}: Draw a card. Activate only if there are four or more card types among permanents you control.

When Speaker of Open Waters enters, create a green and white Aura enchantment token named Moray's Resolve attached to target creature you control. The token has enchant creature and “Enchanted creatures you control get +2/+2 and have trample and lifelink.”

Stinging Swordfish has first strike as long as it's attacking.
When Stinging Swordfish dies, create an Equipment enchantment artifact token named Fish Sword with “Equipped creature gets +3/+1,” “Equipped creature has first strike as long as it's attacking,” and equip {2}. You may attach that token to a creature you control.