msem-instigator

When Skeletal Shredwing enters, target creature can't block this turn.
Revive {5}{R} ({5}{R}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

At the beginning of each upkeep, choose one or more —
• Untap target artifact.
• Untap target creature.
• Untap target land.

Equipped creature gets +0/+3 and has menace. (It can't be blocked except by two or more creatures.)
Equip {3}

Resolute — Skerry Serpent must be blocked if able as long as its power is greater than its base power.

Menace
Whenever an opponent casts a spell, Skhorvall Behemoth gets -2/-2 until end of turn.

Whenever an embattled creature you control dies, you may return Skhorvall Eternal from your graveyard to your hand. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Flying
Whenever Skhorvall Patrol deals combat damage to a player, look at the top card of that player's library.

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.)

Menace
Whenever Skhorvall Warleader attacks, it gets +1/+0 until end of turn for each other attacking Warrior you control.

Sacrifice another creature: Put a +1/+1 counter on Skieryg Menace.

Whenever an opponent is dealt damage by one or more sources you control for the second time each turn, draw a card.

Whenever a player casts an instant or sorcery spell from their hand, you may exile that card as it resolves instead of putting it anywhere else.
Whenever Skill Sketcher attacks, you may cast a card exiled with it. That spell costs {X} less to cast, where X is Skill Sketcher's power.

Skin from Bone deals damage to target creature equal to your fealty to Mountains. (Each Mountain you control counts towards your fealty to Mountains.)

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

When Skittering Atrocity enters, up to one target creature gets -X/-X until end of turn, where X is the number of Horrors you control.

Flying
Spells you cast from anywhere other than your hand cost {2} less to cast.
Spells your opponents cast from anywhere other than their hand cost {2} more to cast.

Reach

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

Whenever Skitterthorns blocks or becomes blocked, creatures you control gain deathtouch until end of turn.

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.

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

{3}{W}: Tap target creature with power 4 or greater.

This spell can't be countered.
{U}: Exile Skulkling. Return it to the battlefield under its owner's control at the beginning of the next end step.
{1}{U}: Until end of turn, Skulkling gets +1/-1 and can't be blocked.
{3}{U}: Draw a card. Create a 1/1 blue Rogue creature token.

{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.