msem-instigator

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.)

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.)

Put up to one target permanent card from your graveyard on top of your library. (Then exile this card. You may play the land later from exile.)

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever you put one or more +1/+1 counters on a creature, add a quest counter.
1, 2 — Create two 1/1 green and white Mouse Soldier creature tokens with vigilance.
3 — Until end of turn, creatures you control get +1/+1 and gain lifelink.
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Exchange control of two target creatures. If an opponent gained control of a Monk you controlled this way, return that creature to its owner's hand.

Enchant creature
Enchanted creature gets +2/+2 and attacks each turn if able.

Return target creature card with mana value 3 or less from your graveyard to the battlefield. You gain 3 life.

Look at the top two cards of your library. Put one into your graveyard and the other back on top.

This spell can't be countered.
Haste
Whenever a creature dealt damage by Ripper of the Fang Den this turn dies, put X +1/+1 counters on Ripper, where X is his power.

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.

Destroy all creatures with mana value 3 or less.

At the beginning of your upkeep, look at the top card of your library. If its mana value is less than or equal to the number of Scouts you control, you may reveal it and draw a card.

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.)

Gain control of up to two target creatures until end of turn. Untap them. They gain haste until end of turn.
Menagerie — If there are five or more creature types among creatures you control, untap all creatures you control. Until end of turn, they gain “{T}: This creature fights another target creature.”

This spell has flash as long as you control a creature with power 4 or greater.
Target creature you control deals damage equal to its power to target creature you don't control.

{T}: Add {C}.
{2}, {T}, Sacrifice Rugged Expanse: Put a +1/+1 counter on target creature. It gains vigilance until end of turn. Activate only as a sorcery.

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.

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 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.)

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.

Target creature you control gains protection from the color of your choice until end of turn. (Then exile this card. You may cast the creature later from exile.)

The next time one or more creatures you control would die this turn, exile those cards. You may play them until the end of your next turn.

Whenever another creature you control enters the battlefield, if its power is greater than Scalebruiser's power, put a +1/+1 counter on Scalebruiser.
As long as Scalebruiser's power is 4 or greater, each other creature you control enters the battlefield with an additional +1/+1 counter on it.