msem-instigator

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.

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.)

Flash
When Slippery Assassin enters, counter target spell if its mana value is less than or equal to Slippery Assassin's power.
Sacrifice another creature: Put a +1/+1 counter on Slippery Assassin.

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.

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

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.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
{2}{B}, Sacrifice Sluiceway Shrieker: Put the bottom card of your library into your hand.

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

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

When Smoldering Husk dies, it deals 2 damage to any target.
{2}{R}: Smoldering Husk gets +2/+0 until end of turn.

Creatures with power less than Sneaking Peak's power can't block it.
At the beginning of your end step, if Sneaking Peak didn't attack this turn, put a +1/+1 counter on it.

Prowess
When Snowline Ascetic enters, you may put target instant or sorcery card from your graveyard on top of your library.

Flying

When Solar Wisp enters, put a +1/+1 counter on target creature.

Flying
Whenever Soli Windreader attacks, tap target creature without flying you don't control.

Flying
When Soli's Blessed enters, judge another target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.
{3}{W}{U}: Tap target creature and put a +1/+1 counter on Solitary Guardian.

You may look at the top card of your library any time.
You may play lands from your graveyard and the top of your library.

When Sorrowslayer enters, put a +1/+1 counter on target creature.
Remove a +1/+1 counter from Sorrowslayer: Trigger a death knell of a permanent you control. Activate only once each turn and only as a sorcery.

Whenever another creature enters, you gain 1 life.

Soul of Misery gets +1/+1 as long as you control a Swamp.
{4}{B}: Target player discards a card. Activate only as a sorcery.

Whenever another creature enters, you may gain 1 life.

Advance {2}{R} (Cast this for {2}{R} to advance it as it enters. {2}{R}: Advance this as a sorcery.)
Haste
Whenever Soulblade Warrior advances, it gets +2/+0 until end of turn.

{1}, Sacrifice a creature: Each opponent loses 1 life and you gain 1 life.