msem-instigator

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.

Flying
When Slighted Spirit enters, detain up to two target creatures. (Until your next turn, those permanents can't attack or block and their activated abilities can't be activated.)

Creatures your opponents control get -4/-0 until end of turn.
Quickdraw {1}{U}{U} (When a creature you control blocks or becomes blocked, you may cast this spell for {1}{U}{U}.)

Ward {2}
Slippery Bunyip can't be blocked except by creatures with Adventures.

Slippery Capuchin can't be blocked.
Whenever Slippery Capuchin becomes the target of a spell or ability, you may change the target of that spell or ability.

Whenever a creature attacks you or a planeswalker you control, that creature's controller mills two cards.

(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.

{T}: Target opponent loses 2 life. Activate only if you gained life this turn.

Whenever you cast an instant, sorcery, or Wizard spell, Slipsand Runemage deals 1 damage to any target.

As long as there are four or more card types among cards in your graveyard, Slipstream Silencer can't be blocked.
Whenever Slipstream Silencer attacks, surveil 1.

Vanguard — Whenever a creature you control attacks alone, you may exile target instant or sorcery card from your graveyard. If you do, you may cast that spell from exile until your next turn. If that spell would be put into a graveyard, exile it instead.

Sludge-Gill Fox can't be blocked as long as it's attacking alone.
Whenever Sludge-Gill Fox deals combat damage to a player, you may draw a card.

Advance {5}{B}{B} (Cast this for {5}{B}{B} to advance it as it enters. {5}{B}{B}: Advance this as a sorcery.)
Whenever Sluiceway Collector advances, put a permanent card from a graveyard onto the battlefield under your control.

Deathtouch
When Slum Scrounger enters, put up to two target creature cards in your graveyard on top of your library in any order.

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Slums Thug gets +1/+1 and has menace as long as you've gained life this turn.

When Slyten Analyst enters, you may search your library for a card, then shuffle and put that card on top. If you do, you lose 2 life.

Whenever Slyten Connoisseur attacks, crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)
Once each turn, when an artifact you control dies, you may pay 1 life. If you do, draw a card.

Flying
{R}: Slyten Ignitor gets +1/+0 until end of turn.

Whenever Slyten Jewel Runner attacks, target creature can't block until end of turn.
Augmented — At the beginning of your end step, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on Slyten Jewel Runner.

Choose target creature you don't control. When that creature dies this turn, draw a card. Target creature you control fights that creature.

When Smashing Brute enters, target nonbasic permanent loses all abilities until your next turn.
Foresight — Whenever you draw your second card each turn, you may exile Smashing Brute. If you do, return it to the battlefield.

Smelting Breath deals 5 damage to target creature. Destroy up to one Equipment attached to that creature.

Destroy target creature with power 4 or greater.

Exile target permanent. Smite the Unruly deals damage equal to that permanent's mana value to its controller and you gain that much life.