msem-instigator

At the beginning of combat on your turn, if you control a creature with power greater than its base power, Satyr Trailblazer gets +2/+0 until end of turn.

When Savannah Huntsman enters, it deals X damage to target creature or planeswalker, where X is the number of counters among permanents you control.

Whenever you cast a spell, if mana from an artifact was spent to cast it, exile the top card of your library. You may play that card until you exile another card with Savant of Cables.

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.)

Whenever you cast a spell, you may pay {1}. If you do, put a storage counter on Savings Broker.
Remove X storage counters from Savings Broker: Add {C} for each storage counter removed this way. You gain X life.

Each instant and sorcery card in your graveyard has reprise. The reprise cost is equal to its mana cost. (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)
Reprising spells you control can't be countered.

When Scaled Lurker enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Deathtouch
Inspired — Whenever Scar Tattooist becomes untapped, you may have target creature get -1/-1 until end of turn.

Whenever Scarhide, Arsenal Crafter attacks, create a token that's a copy of an Equipment attached to Scarhide and attach the token to Scarhide. When you can't, arm it. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

{2}{G}: Scarred Brawler gets +2/+2 until end of turn.

First strike
Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)

Whenever Scathing Critics deals combat damage to a player or planeswalker, put a +1/+1 counter on it.

Whenever another creature dies, you gain 1 life.

Reach
When Scavenging Pack enters, you may destroy target artifact with mana value 2 or less.

Flash
When Scholar of Reflections enters, you may switch target creature's power and toughness until end of turn.

Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
Whenever you put one or more -1/-1 counters on Scion of Fiends or another creature, Scion of Fiends deals that much damage to each opponent.

When Scion of Pestilence enters, create a black enchantment token named Blight with “At the beginning of your upkeep, you lose 1 life.”

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.)

Flying
Whenever you cast an instant or sorcery spell, Scourge of the Sun gets +1/+0 until end of turn. If you spent four or more mana to cast that spell, Scourge of the Sun gets an additional +1/+0 until end of turn.

Menace
Sacrifice another artifact: Scrap Buggy becomes an artifact creature until end of turn.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

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

Trample, prowess

Ward {2}
Once each turn, if you would create one or more tokens, create that many of those tokens plus one instead.

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.)

{2}{R}: Target creature can't block this turn.