msem-instigator

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

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.)

Vigilance
Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)

Flying, vigilance, lifelink
During each of your turns, you may cast a multicolored spell from your graveyard.

Target creature you control fights target creature you don't control. (Then exile this card. You may cast the creature later from exile.)

Trample
Savage Mammoth gets +1/+1 for each land you control.
Ride {4}{G} ({4}{G}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Untap all creatures and lands you control during each other player's untap step.
Ascend {4}{R}{R}{R} ({4}{R}{R}{R}: Exile this creature, then return it to the battlefield transformed. Ascend only as a sorcery.)

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.

(Transform this if it's not attached to a creature. Pay {1}{R} as a sorcery to unattach it.)
Enchant creature you control
Scale Bearer's rider gets +4/+3 and has flying and haste.
Whenever Scale Bearer's rider attacks, you may pay {2}{R}. If you do, it deals damage equal to its power to target creature or planeswalker.

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

Enchant player
Whenever enchanted player taps a nonbasic land they control, that land doesn't untap during its controller's next untap step.

Whenever Scavenger of the Old Bay deals combat damage to a player, draw a card.
Ride {1}{U} ({1}{U}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Scavenging Soldier has first strike as long as it's attacking.
Attain {3}{W} ({3}{W}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Scoundreleo enters the battlefield with a +1/+1 counter on it if a creature you controlled dealt combat damage to a player this turn.

Double strike
Creatures you control have trample.
Excess noncombat damage that would be dealt by sources you control to permanents an opponent controls is dealt to that player instead.

Flying, haste
Ride {1}{R} ({1}{R}: Transform this and attach it to target creature you control without a Mount. Ride only as a sorcery.)

As an additional cost to cast this spell, pay 3 life and sacrifice a creature.

Flying
Dragon spells and Adventure spells you cast cost {1} less to cast.

Counter target permanent spell. (Then exile this card. You may cast the creature later from exile.)

Until end of turn, target creature gains “When this creature is dealt damage, destroy it.” (Then exile this card. You may cast the creature later from exile.)

At the beginning of your upkeep, if six or more cards are in your graveyard, you may transform Scuttling Gnat.

Another target player reveals their hand. You may choose a nonland card from it. That player discards that card.
Fuse (You may cast one or both halves of this card from your hand.)

Seaside Skimmer can't be blocked if you've cast a Dragon spell or Adventure spell this turn.

Exile target creature or planeswalker card from a graveyard. Search its controller's hand, graveyard, and library for any number of cards with the same name as that card and exile them. Then that player shuffles.

Look at the top two cards of target player's library. Put one of those cards on the bottom of their library and the rest on top.
Fuse (You may cast one or both halves of this card from your hand.)