msem-instigator

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

(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.

Glitch {2} (Remove one [restriction] for each time you pay the glitch cost.)
Target creature gets +3/+3 until end of turn [if it has trample]. Then put a trample counter on that creature.

Enchant creature
Enchanted creature gets +4/+4 and has trample.
When enchanted creature dies, create a 4/4 green Beast creature token with trample.

Enchant player
When Scaleblight's Quarry enters, you may have target creature you control deal damage equal to its power to target creature enchanted player controls.
Whenever enchanted player becomes the target of a spell you control, you gain 1 life.

Put a +1/+1 counter on target creature. That creature gains first strike until end of turn.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Equipped creature gets +1/+1.
Equipped creature has “When this creature dies, if it's not a token, create a token that's a copy of it except it's a colorless Spirit Dragon with flying in addition to its other abilities.”
Equip {2}

When Scanning Module enters, crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)
Equipped creature gets +1/+1.
Equip {1}

Remove a -1/-1 counter from target creature. That creature gets +2/+2 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.

Target creature you control gains haste until end of turn. Create a token that's a copy of that creature, then exile that token.

Choose one —
• Put a -1/-1 counter on target attacking or blocking creature.
• Scarring Censure deals 2 damage to target attacking or blocking creature.

Harness (You may tap a creature you control as you cast this spell. If you do, reduce this spell's mana cost by that creature's power.)
Target creature gets -X/-X until end of turn.

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.
Menagerie — If there are five or more creature types among creatures you control, scry 3.

Scathing Review deals 2 damage to target creature. If you control an artifact, Scathing Review deals 2 damage to that creature's controller.

Target player reveals their hand. You choose a nonland card from it. That player discards that card. Create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Counter target spell. Tap all lands that spell's controller controls and that player loses all unspent mana.

Put target creature on top of its owner's library. All other creatures that player controls get -2/-2 until end of turn.

Exile target creature. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Target permanent you control gains hexproof and indestructible until end of turn. You gain 2 life.

Scavenger Holdout enters tapped.
When Scavenger Holdout enters, you may pay {3}. If you do, create two 1/1 green Scout creature tokens.
{T}: Add {C}.

Exile target creature with mana value 2 or less.

As an additional cost to cast Scavenger's Skill, you may reappropriate. (To reappropriate, exile exactly two cards from your hand and/or graveyard.)
Scavenger's Skill deals 3 damage to target creature or planeswalker. When that permanent dies this turn, if Scavenger's Skill's additional cost was paid, draw a card.

Draw three cards, then manifest a card from your hand. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Choose one or both —
• Scene to Cinders deals 2 damage to each token creature.
• Scene to Cinders deals 2 damage to each nontoken creature.