msem-instigator

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.

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.

Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)
Whenever Scavengermobile deals combat damage to a player, choose land or nonland, then rediscover a card of that kind. (Look at the top card of your library. You may reveal it and put it into your hand if it's a card of the chosen type. Otherwise, put it back or into your graveyard.)

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.

Enchant creature
Enchanted creature gets +2/-2.

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

Scoundreleo enters 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.

Look at the top X cards of your library, where X is the number of instant and sorcery cards in your graveyard. You may reveal an instant or sorcery card from among them and put it on top of your library. Then put the rest on the bottom of your library in a random order.

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

When Sealed Riftway enters, exile up to one target card from a graveyard.
{2}, {T}, Sacrifice Sealed Riftway: Exile target player's graveyard. Draw a card.

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.