msem-instigator

If a creature entering the battlefield under your control causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
{1}{U}, {T}: Exile another target creature. Return it to the battlefield under its owner's control at the beginning of the next end step.

Vanguard — Whenever a creature you control attacks alone, you may cast a spell with mana value 3 or less from your hand without paying its mana cost.

({T}: Add {G} or {W}.)
Sungrace Meadows enters the battlefield tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Return target creature to its owner's hand. Its controller loses 1 life.

As Sunlit Highland enters the battlefield, you may pay 2 life. If you don't, Sunlit Highland enters the battlefield tapped.
{T}, Sacrifice Sunlit Highland: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Sunrise Orchard enters the battlefield tapped.
{T}: Untap another target land you control.

Flash
Flying
When Sunset Herald enters the battlefield, if it was cast, return to the battlefield all creature cards from your graveyard that were put there from the battlefield this turn.

({T}: Add {W}.)
Sunstage enters the battlefield tapped.
When Sunstage enters the battlefield, creatures you control get +0/+1 until end of turn.

{T}, Pay 1 life: Add {R}.
{T}, Pay 1 life, Sacrifice Sunwashed Spires: Search your library for a Mountain card, put it onto the battlefield tapped, then shuffle.

When Sunwright Scion enters the battlefield, put a +1/+1 counter on each other creature you control.
At the beginning of each combat, you may have target creature with a +1/+1 counter on it gain your choice of vigilance, lifelink, or trample until end of turn.

Creatures you control get +2/+2 and gain trample until end of turn. If you cast this spell from exile, creatures you control get an additional +2/+2 until end of turn.
Prophecy {2}{G}{G} (Once each turn, you may exile a card with prophecy as you reveal it. When you do, you may cast it for its prophecy cost as long as it's exiled.)

Prowess
Whenever you cast a noncreature spell, Surestrike Elite gains first strike until end of turn.

As an additional cost to cast this spell, torment yourself. (You lose 3 life unless you discard a card or sacrifice a nonland permanent.)
Destroy target creature.

Whenever a creature you control becomes the target of a spell, that creature gets +3/+3 until end of turn.

Deception {U}{B} ({U}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Pay 1 life, Choose a creature card name you haven't chosen for Suzume Oshiruko this turn: Return another creature you control with the chosen name to its owner's hand.

Each other Rogue creature you control enters the battlefield with an additional +1/+1 counter on it.
Remove a +1/+1 counter from a creature you control: That creature can't be blocked this turn.

Swiftwater Cliffs enters the battlefield tapped.
When Swiftwater Cliffs enters the battlefield, you gain 1 life.
{T}: Add {U} or {R}.

Sword deals 2 damage to any target.
Fuse (You may cast one or both halves of this card from your hand.)

Equipped creature gets +2/+2 and protection from blue and from black.
Whenever equipped creature deals combat damage to a player, return up to one target creature card and up to one target instant or sorcery card from your graveyard to your hand.
Equip {2}

First strike
When Sworn Cohort dies, you may search your library for a legendary card, reveal it, put it into your hand, then shuffle.

At the beginning of your upkeep, you may sacrifice Sylph Spawning. If you do, create three 1/1 blue Nymph creature tokens with flying.

Flying
Synchronous Hellkite enters the battlefield with a +1/+1 counter for each other artifact you control.
Sacrifice three artifacts: Return Synchronous Hellkite from your graveyard to the battlefield.

Flying
When Syrina, the Dragon Queen enters the battlefield, gain control of target nonland permanent for as long as you control Syrina, the Dragon Queen.
{2}{U}: Exile Syrina, the Dragon Queen. Return her to the battlefield at the beginning of the next end step.

Enchant creature
When Sythian Scripture enters the battlefield, put two +1/+1 counters on enchanted creature.
Enchanted creature gets +1/+1 and has indestructible and lifelink if you controlled a white legendary creature or planeswalker as you cast Sythian Scripture.