msem-instigator

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.

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

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

Flying
{1}{U}, Sacrifice Scholar's Assistant: Draw a card.

Target creature you control gets +1/+2 until end of turn. If that creature is white, create a white Aura enchantment token with enchant creature and “Enchanted creature has first strike” attached to that creature.

Scorch deals 3 damage to any target.

Whenever you cast a spell, Scorned Figurant gets +1/+1 until end of turn.

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

Look at the top five cards of your library. You may reveal a Scout or land card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Prevent all damage that would be dealt by creatures this turn.

Target player discards a card. If they didn't discard an artifact card, you gain 3 life.

{2}{B}, {T}, Sacrifice Sculler's Oar: Return up to two target creature cards from your graveyard to your hand.

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.

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.

Seafoam Slasher gets +1/+1 and has deathtouch as long seven or more cards are in your graveyard.
Cycling {2} ({2}, Discard this card: Draw a card.)

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Target creature or planeswalker an opponent controls phases out. If you're in a renaissance, exile it instead.

Choose target card in a graveyard other than a basic land card. Search its owner's graveyard, hand, and library for any number of cards with the same name as that card and exile them. Then that player shuffles.
Scry 1.

When Sealed Evil in a Cage enters the battlefield, exile target creature an opponent controls with mana value 3 or greater until Sealed Evil in a Cage leaves the battlefield.

Sear Flesh deals 3 damage to target creature or planeswalker. If you've cast another spell this turn, it deals 5 damage instead.

Searing Blasphemy deals 2 damage to target creature. If that creature is an Angel, Searing Blasphemy deals 5 damage instead.

Target creature gains winnow until end of turn if you attacked this turn. Searing Insult deals 2 damage to that creature. (Damage dealt to it also causes its controller to lose that much life.)

Reverberate {3}{R} (When you cast this spell, copy it if you paid its reverberate cost. You may choose new targets for the copy.)
Searing Pulse deals 2 damage to any target.

Target permanent you control deals 2 damage to any target.
Inscribe {2}{R}{R} ({2}{R}{R}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)