msem-instigator

Create a 1/1 green Squirrel creature token.
The next creature spell you cast this turn can be cast as though it had flash. As you cast that spell, it gains voracious 2. (As it enters, you may sacrifice up to two artifacts and/or creatures. That creature enters with that many +1/+1 counters on it.)

Advance {3}{R}{R} (Cast this for {3}{R}{R} to advance it as it enters. {3}{R}{R}: Advance this as a sorcery.)
Flying, haste
Whenever Skiviar Scraplord advances, put a +1/+1 counter on it.

{T}, Discard your hand: If two or more cards were discarded this way, search your library for a card and put that card into your hand, then shuffle.

Equipped creature gets +2/+2.
Whenever equipped creature deals combat damage to a player, you may put a permanent card with mana value 2 or less from your hand onto the battlefield.
Equip {2}

Skylight Fortress enters tapped.
When Skylight Fortress enters, you may search your library for a card named Skylight Fortress, reveal it, put it into your hand, then shuffle.
{T}: Add {C}.

Flying, trample, haste
Whenever a land you control enters or a land is put into your graveyard from the battlefield, Skyscreecher Dragon deals 2 damage to each opponent.

Trample

Whenever you tap a creature for mana, put a +1/+1 counter on that creature.
{T}: Add {G}.

As an additional cost to cast this spell, discard a card and sacrifice a nonland permanent.
Draw three cards.

Haste
Whenever a creature attacks, Slashing Pangolin gets +1/+1 until end of turn.

Vanguard — Whenever a creature you control attacks alone, target creature can't block this turn.

When Slaug's Warhowler enters, create a 1/1 red Goblin creature token with haste.
When Slaug's Warhowler dies, you may discard a card. If you do, draw a card.

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Slaughtered Steps Taskmaster attacks, you may sacrifice another creature. If you do, Slaughtered Steps Taskmaster gets +2/+0 until end of turn.

Slaughterkeg can't attack or block.
While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least Slaughterkeg if able.
When Slaughterkeg dies, draw a card.

Slay Them in the Aisles deals 2 damage to each non-Actor creature.

Target creature blocks this turn if able. You may have it gain reach until end of turn.
Draw a card.

Whenever Sledgesuit Prospector attacks, choose any number —
• Sacrifice an artifact. If you do, put a +1/+1 counter on Sledgesuit Prospector.
• Discard a card. If you do, create a Treasure token.

Enchant land
Whenever enchanted land is tapped for mana, its controller adds {G}.
{G}, Sacrifice Sleeping Dryads: Draw a card.

You may change the targets of target instant spell, sorcery spell, or activated ability.

Create two 1/1 red and white Warrior creature tokens. Those tokens gain first strike until end of turn.

Identity — As long as you control at least two other creatures that share a creature type with Slicing Steer, Slicing Steer and creatures you control that share a creature type with it get +1/+0 and have menace.

Equipped creature has “{1}, {T}: This creature deals 1 damage to any target.”
Whenever equipped creature deals damage to a creature with power 5 or greater, sacrifice Sling of the Meek. If you do, destroy that creature.
Equip {3}

{1}{R}: Target creature can't block Slippery Salamander this turn.

(Add a quest counter as this enters. Sacrifice after 3.)
Once each turn, when you cast an instant or sorcery spell, you may add a quest counter.
Slipsand Expedition deals damage equal to the number of quest counters on it to any target.
Add {R}{R}{R}.

Menagerie — {1}{G}: Slipsand Hornshell gains indestructible until end of turn. Tap it. Activate only if there are five or more creature types among creatures you control.