msem-instigator

When Skhorvall Raider enters, if you control an embattled creature, Skhorvall Raider deals 2 damage to any target. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Whenever another creature with mana value 2 or less you control enters, tap target creature an opponent controls.

Reach
Whenever another creature you control dies, surveil 1.
{T}, Sacrifice a non-Spider creature: Create a 1/2 green Spider creature with reach.

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.

Skulking Claw can't be blocked by creatures with greater power.
Skulking Claw gets +1/+0 for each unblocked attacking creature you control.

Flying
Death knell — Skullhoarder Dragon gets +2/+0 until end of turn. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Flash
Flying
Whenever you cast a spell during an opponent's turn, create a Weapon token. When you do, you may attach it to another target creature with flying. (It's an Equipment artifact token with equip {2} and “Equipped creature gets +1/+1”.)

Flying
Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
Your opponents can't cast spells during combat and can't activate abilities during combat unless they're mana abilities.

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever Skysovereign Griffin attacks, it gets +1/+0 until end of turn for each other attacking creature with flying you control.

Flying
When this creature enters, target creature gains flying until end of turn.
Arise {3}{W}{W} ({3}{W}{W}, Exile this from your graveyard as a sorcery: Create a black token copy of it that's also a Zombie and can't block.)

Resolute — At the beginning of combat on your turn, if Skyward Gaveller's power is greater than its base power, it gains flying until end of turn.

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.

Deathtouch, menace
Slayer of the Famed must be blocked each combat if able.

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.

Flying, vigilance

Vanguard — Whenever a creature you control attacks alone, it gets +1/+1 until end of turn. Untap that creature.

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

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

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.

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.

{2}, Remove a +1/+1 counter from a creature you control: Draw a card.

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.

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.