msem-instigator

Poisonous 4 (Whenever this creature deals combat damage to a player, that player gets four poison counters.)
At the beginning of combat on each of your turns, if an opponent is poisoned, creatures you control gain trample until end of turn.

Remove a -1/-1 counter from target creature. That creature gets +2/+2 until end of turn.

{2}{G}: Scarred Brawler gets +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.

Attacking creatures get -3/-0 until end of turn.

As Scorched Copse enters, you may tap an untapped creature you control. If you don't, Scorched Copse enters tapped.
{T}: Add {R} or {G}.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Scorchland Vandal attacks each combat if able.

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
When Scourge of the Deadlands enters, if it engorged a creature card, each other player sacrifices a creature.

Reveal the bottom four cards of your library. Choose up to one permanent card with mana value 3 or less from among them and put it onto the battlefield. Put the rest on the bottom of your library in any order.

When Scrapgear Contraption dies, you may put a +1/+1 counter on target creature.

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.

When Scrapyard Aberration enters, you may sacrifice another artifact. If you do, target creature gets -2/-2 until end of turn.

When Scribal Puppeteer enters, create two 1/1 black Puppet creature tokens with “At the beginning of your upkeep, you lose 1 life.”

When Scrivener of Sha'Iv enters, draw a card and adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)

Haste
Frenzy 2 (Whenever this creature attacks and isn't blocked, it gets +2/+0 until end of turn.)

Play with the top card of your library revealed.
You may cast Elemental spells from the top of your library.

Defender
{1}{U}: Sea Wall gets +0/+1 until end of turn.
Whenever Sea Wall perseveres, you may return target creature an opponent controls to its owner's hand. (A creature perseveres when it survives damage.)

{U}, Sacrifice Seal of Insights: Look at the top four cards of your library. Put one into your hand and the rest on the bottom of your library in any order.

Cards in graveyards lose all abilities.
Cards in graveyards can't be the target of spells or abilities.

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.)

Reveal the top five cards of your library. You may put an instant or sorcery card from among them into your hand. Put the rest into your graveyard.

Search your library for an enchantment card, reveal it, put it into your hand, then shuffle.

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.