msem-instigator

Haste
Sixpod Sprinter can't be blocked except by creatures with flying or reach.

Advance {3}{R} (Cast this for {3}{R} to advance it as it enters. {3}{R}: Advance this as a sorcery.)
Whenever another artifact creature you control enters or a permanent you control advances, Skalorian Orbguard deals 1 damage to any target.

Haste
Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
Legendary creatures you control have haste.

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.)

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.

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

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

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.

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

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.

Improve {1}{B/R} ({1}{B/R}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
At the beginning of each player's combat, you may have that player create two goaded 1/1 red Goblin creature tokens with haste. Exile those tokens at end of combat. (Until your next turn, they attack each combat if able and attack a player other than you if able.)

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.

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.

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.

Slinking Raider can't be blocked by creatures with greater power.
Whenever Slinking Raider deals damage to a player or noncreature permanent, put a +1/+1 counter on it.
Surpass {5}{R} ({5}{R}: Transform this creature.
This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

{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.
1, 2 — Slipsand Expedition deals damage equal to the number of quest counters on it to any target.
3 — Add {R}{R}{R}.

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

Whenever Slithering Eyes deals damage to a player, you may exile that many cards from the top of your library. Until the end of your next turn, you may play those cards.

First strike
{2}{R}: Monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)