msem-instigator

Until end of turn, target creature you control gets +1/+1 and target creature an opponent controls gets -1/-1.

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.

Rhapsody {3}{W}{W} (Pay {3}{W}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Players can't search libraries unless they pay {X}, where X is Skytouch Distorter's power.

Whenever Slaffield Workgate or another enchantment you control enters, create a 0/2 white Ox creature token.
{3}{W}: Return another target enchantment you control to its owner's hand.

Haste
Whenever a creature attacks, Slashing Pangolin gets +1/+1 until end of turn.

Slaughterkeg can't attack or block.
While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least Slaughterkeg if able.
When Slaughterkeg dies, draw a card.

Enchant land
Whenever enchanted land is tapped for mana, its controller adds {G}.
{G}, Sacrifice Sleeping Dryads: Draw a card.

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.

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

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.

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

You draw a card and you lose 1 life. Exile Small Luxuries.
At the beginning of your upkeep, you may return Small Luxuries from your graveyard to your hand.

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

Target opponent discards two cards. You gain 2 life. (Then exile this card. You may cast the creature later from exile.)

Enchant artifact or creature
Enchanted permanent doesn't untap during its controller's untap step.
Whenever you make first contact, scry 1. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

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

Target creature gets -X/-X until end of turn, where X is the number of cards in your graveyard. If that creature would die this turn, exile it instead.
Cycling {B} ({B}, Discard this card: Draw a card.)

Create a 1/1 blue Bird creature token with flying.
Inscribe {2}{U} ({2}{U}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

Bleed {0} (You may cast this spell for its bleed cost if an opponent has lost life this turn.)
Look at target player's hand.
Draw a card.

({T}: Add {U} or {B}.)
Sodden Cavern enters tapped.

Foretell {B}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
Haste
Whenever Sofia deals combat damage to an opponent, exile the top card of that player's library face down and look at it. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast that spell. Then foretell Sofia. It costs {0} to foretell this way.

Solar Flare deals 3 damage to any target. You gain 3 life.

Whenever you make first contact, return target creature card from your graveyard to the battlefield. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Destroy target artifact or enchantment. You gain 4 life.

Soli Sanctuary enters tapped.
Satrapies you control have “{T}: Add {W} or {U}.”