msem-instigator

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Madness {1}{G} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Spirited (When this creature enters, you may activate one of its activated abilities without paying its costs.)
{1}{R}, Discard a red card: Roggar deals 2 damage to any target. This damage can't be prevented.
{2}{R}, Exile a red card from your graveyard: Create two tapped 1/1 red Elemental creature tokens.

Target opponent looks at the top six cards of your library and separates them into a face-down pile and a face-up pile. Choose a pile, then play any number of cards from it without paying their mana costs. Put the rest of the cards into your graveyard.

Choose one —
• Counter target spell unless its controller pays {2}.
• Create a tapped token that's a copy of target token you control.

{1}{G}, {T}, Discard a card: Another target creature you control gets +X/+X until end of turn, where X is 4 minus that creature's power.

Whenever Roving Dreadnought attacks, you may salvage a card that was put into your graveyard this turn. (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.)

Until end of turn, target creature you control gets +2/+0 and gains “When this creature dies, mill two cards, then return it to the battlefield under its owner's control.”

Haste
Ruin Shark attacks each turn if able.
Ruin Shark gets +1/+0 and has first strike as long as you've drawn two or more cards this turn.

{1}, Sacrifice Ruinous Proselyte: Destroy target artifact or nonbasic land.

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

Target creature you control gets +1/+1 until end of turn. It deals damage equal to its power to target creature you don't control.
Madness {3}{G} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

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.

Choose one —
• Tap target creature.
• Untap target creature and remove it from combat.
Draw a card.

Each opponent loses 3 life and you gain 3 life.
Whenever you cast your second spell each turn, if Salome's Intervention wasn't put into your graveyard this turn, return it from your graveyard to your hand.

When Salty Swab enters, 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.

You may sacrifice three artifacts rather than pay this spell's mana cost.
Exile three artifact cards from your graveyard: Return Salvage Titan from your graveyard to your hand.

Flying
Whenever you cast an artifact or enchantment spell, tap target artifact or creature an opponent controls. It doesn't untap during its controller's next untap step.

As long as you control exactly two creatures, those creatures get +2/+1 and have lifelink.

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

As Scion of Silence enters, choose a nonland card name.
Other permanents with the chosen name lose all abilities.

Menace (This creature can't be blocked except by two or more creatures.)
Whenever another creature dies, you may salvage a 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.)

Concord — {1}{G}: Until end of turn, Seadrake Rider gets +2/+3 and must be blocked if able. Activate only during your turn, only once each turn, and only if there are four or more card types among permanents you control.

When Seafloor Cache enters and when you sacrifice it, create a Treasure token.
{1}{R}, Sacrifice Seafloor Cache: Draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

When Seafloor Casket enters and when you sacrifice it, target player mills two cards.
{1}{U}, Sacrifice Seafloor Casket: Draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

When Seafloor Shrine enters and when you sacrifice it, create a 1/1 white Merfolk creature token.
{1}{W}, Sacrifice Seafloor Shrine: Draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)