msem-instigator

When Dawson's Loot enters, mill two cards, then draw a card.
{1}, {T}, Sacrifice Dawson's Loot: Add one mana of any color.

Dawson's Marauder can't block.
When Dawson's Marauder attacks, it can't be blocked this turn unless defending player sacrifices an artifact.

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.

{2}{G}{U}: 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, draw a card.

Target instant or sorcery card in your graveyard gains flashback until end of turn. Its flashback cost is equal to its mana cost reduced by {2}.
Conjure a card named Fatigue and put it on top of your library. (It's a colorless sorcery that costs {2} with “Draw a card.”)

Destroy target creature that's not enchanted and isn't an enchantment.

Enchant creature
When Deathless Conscription enters, untap enchanted creature.
You control enchanted creature.

Deep-Sea Terror can't attack unless seven or more cards are in your graveyard.

Creatures you don't control get -1/-0 as long as their controller is cursed.

Flash

Whenever you draw your second card each turn, create a 1/1 blue Tentacle creature token.
{3}{G}, Sacrifice two creatures: You gain 1 life and draw a card. Activate only during your turn.

{4}{B}: Depthlight Beacon gets +1/+1 and gains lifelink until end of turn.
Cycling {2/B} ({2/B}, Discard this card: Draw a card.)

When Depthlight Brute enters, if you control three or more artifacts, each opponent loses 3 life and you gain 3 life.

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.)

Trample
When Depthlight Frontliner enters, you may salvage up to one instant card and up to one sorcery card. (Exile those cards 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.)

Deathtouch
When Depthlight Salvager enters, you may salvage a creature card with mana value 3 or less. (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.)

Spells your opponents cast cost {1} more to cast.
Spells you cast cost {1} less to cast.

Concord — When Dolphin Rider enters, if there are four or more card types among permanents you control, you gain 5 life.

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.

Primal—Reappropriate green. (During your turn, you may cast this spell by exiling two green cards from your hand and/or graveyard instead of playing a land.)
When Dovon's Masterwork enters, return target land card from your graveyard to the battlefield tapped.

Enchant opponent
When Down with the Ship enters, enchanted player discards a card unless they sacrifice a creature.
{1}{B}, Sacrifice Down with the Ship: Return target creature card from your graveyard to your hand.

Pressure {3}{U} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Return target creature to its owner's hand. If this spell was cast for its pressure cost, put that creature into its owner's library second from the top instead.

Instant, sorcery, and Dragon cadence (Whenever you cast an instant, sorcery or Dragon spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)
{R}, {T}, Discard a card: Draw a card.

Each creature card you own that isn't on the battlefield has madness. The madness cost is equal to its mana cost. (If you discard a card with madness, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)
{T}, Discard a card: Dragonlord's Shrine deals 2 damage to any target.

Pressure {G} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Return target card from your graveyard to your hand. Exile Drawn to the Light.