msem-instigator

Heroic — Whenever you cast a spell that targets Setessan Avenger, create a 1/1 green Nymph Dryad enchantment creature token with “{T}: Add {G}.”
Whenever Setessan Avenger deals combat damage to a player, untap all lands and Dryads you control.

As long as it's your turn, Seto San is a 3/3 Human Warrior creature with indestructible.
[+1]: Up to one target creature you control gains lifelink until end of turn.
[0]: Create a 1/1 white Warrior creature token.
[–X]: Search your library for an Aura or Equipment card with mana value X and put it onto the battlefield, then shuffle.

When Settlement Establishment enters, draw a card, then choose a card name.
Whenever an opponent casts a spell with the chosen name, counter that spell, then that opponent creates a Plains token.

When Seven Deadly Sins has seven or more sin counters on it, sacrifice it.
{B}{B}, Put a sin counter on Seven Deadly Sins: Destroy target creature. This ability costs {1} more to activate for each sin counter on Seven Deadly Sins.

Whenever equipped creature deals combat damage to a player, return to your hand all cards from your graveyard that were put there this turn.
Equip {3}

When Sewer Dweller enters or dies, create a 1/1 black Rat creature token with “This creature can't block.”

(Transcend as a sorcery to gain that type and a +1/+1 counter.)
Ward {2}
{2}{U}: Demigod — Exchange a card in your hand and a noncreature, nonland card in your graveyard.
{6}{U}: God — Exchange control of two target permanents that share a card type.

When Sha'Iv's Scout enters, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Whenever an Aura you control enters, target creature can't block this turn.

{U}{R}{W}, Discard a card named Sha'Iv, God of Order: Sha'Iv gains indestructible and becomes a God creature in addition to its other types.
Whenever Sha'Iv enters or attacks, choose target creature an opponent controls. Untap it, then tap each other creature that player controls. They don't untap during their controller's next untap step.

Shadow Ball deals 2 damage to target creature or planeswalker and 2 damage to its controller. You gain 2 life.

Target creature phases out. Its controller sacrifices a creature. (Treat the phased out creature and anything attached to it as though they don't exist until its controller's next turn.)

Flash
When Shadow Stalker enters, for each player, look at the top card of that player's library. You may have that player put that card into their graveyard.

When Shadowbinder Touka enters or attacks, exile up to one target creature card from a graveyard.
You may play creature cards exiled with Touka.
Sacrifice another creature: Add two mana in any combination of colors. You can't spend this mana to cast spells from your hand. If this mana is spent to cast a creature spell, that creature enters with a finality counter on it.

When Shadowstrider dies, create a 2/2 colorless Spirit creature token.

Draw two cards. You lose 2 life. Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Discard your hand. Draw cards equal to the number of creatures that died this turn.

When Shambling Gutless enters, target player discards a card.

Shambling Hive power and toughness are each equal to the number of Insects you control.
Shambling Hive has vigilance as long as you control four or more Insects, and has trample as long as you control eight or more Insects.

Choose two —
• Each opponent sacrifices a creature with mana value 3 or less.
• Each opponent sacrifices an enchantment with mana value 3 or less.
• Exile each opponent's graveyard.
• You gain 3 life.

When Shara, Prime Geneticist enters, if X isn't 0, create two X/X green Mutant creature tokens.
[+1]: Surveil 2. At the beginning of your next end step, untap up to one permanent.
[–2]: Conjure a card named Test Run into your hand. (It's a sorcery that costs {X}{G} with “Create an X/X green Mutant creature token. Draw a card.”)
[–7]: Search your library for a card and put it into your hand. Repeat this process once for each token you control. Then shuffle.

{T}: Each player draws a card.

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Spell you cast cost {1} less to cast as long as it's not your turn.

Flash
Unveil {3}{B}{G} ({3}{B}{G}: Transform this. Unveil only as a sorcery.)

Destroy target creature if it has mana value 4 or greater. If Shatter Facade was cast from exile, destroy that creature if it has mana value 3 or less instead.
Orchestrate {B} (You may exile this card from your hand anytime you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

Equipped creature gets +1/+1.
Whenever equipped creature becomes the target of a spell or ability an opponent controls, you may return Shawl of Warding to its owner's hand. If you do, counter that spell or ability.
Equip {2}