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.

{2}: Other creatures you control get +1/+0 until end of turn.
Whenever Sun-Crowned Flagship attacks, each attacking creature you control gains trample until end of turn.
Crew 7 (Tap any number of creatures you control with total power 7 or greater: This Vehicle becomes an artifact creature until end of turn.)

Whenever you gain life for the first time each turn, draw a card.
{3}{G}{W}: You gain life equal to the greatest toughness among creatures you control.

When Sundering Arcanist enters, you may destroy target artifact or enchantment.
If you would draw a card, you may sacrifice a land and mill four cards instead. If you do, return Sundering Arcanist from your graveyard to your hand.

As Sunflower Fields enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {R}, {G}, or {W}.

Deathtouch
At the beginning of your end step, if you control no Sharks, create a 1/1 blue and black Demon Shark creature token with “This creature can't block” and “When this creature deals combat damage to a player, sacrifice it. If you do, draw a card.”

Sunken Homestead enters tapped.
{T}: Add {B}.
{2}{B}: Until end of turn, Sunken Homestead becomes a 2/2 Zombie creature with “When this creature dies, return it to the battlefield.” Activate only if you're horrific.

Primal {1}{W}{W} (During your turn, you may cast this spell for {1}{W}{W} instead of playing a land.)
Double strike
When Sunken Slasher enters, if you didn't play a land this turn, put a +1/+1 counter on it.

As Sunless Ridge enters, you may tap an untapped creature you control. If you don't, Sunless Ridge enters tapped.
{T}: Add {B} or {R}.

You gain life equal to the number of creatures you control.
Each opponent loses life equal to the number of creatures they control.
Destroy all creatures, then exile all graveyards.

Sunlit Fissure enters tapped.
{T}: Add {G} or {W}.
{2}{G}{W}: Until end of turn, Sunlit Fissure becomes a 3/5 green and white Elemental creature with with vigilance and “Whenever this creature attacks or blocks, torment yourself.” It's still a land. (To torment yourself, lose 3 life unless you discard a card or sacrifice a nonland permanent.)

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

({T}: Add {W}.)
As Sunlit Meadow enters, you may pay 1 life. If you don't, Sunlit Meadow enters tapped.
Basic lands you control have “{T}: Add {W}.”

Sunlit Ruins enters tapped unless you control a Swamp.
{T}: Add {G} or {W}.

Flying, haste
Assault {1}{R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on a creature you control, you may return Sunnula's Firebird from your graveyard to your hand.

Equipped creature has “{T}: This creature deals damage equal to its power to any target.”
Equip {4}

Sunrazed Ruins enters tapped.
{T}: Add {W}.
{2/W}{2/W}: Sunrazed Ruins becomes a 2/3 white Elemental creature with lifelink until end of turn. It's still a land.

Sunrise Bluffs enters tapped.
{T}: Add {R}.
You may untap Sunrise Bluffs during each other player's untap step. Whenever you do, you lose 1 life.

Sunrise Orchard enters tapped unless you control a basic land.
As Sunrise Orchard enters, choose a color.
{T}: Add one mana of the chosen color.

Sunrise Prairie enters tapped.
{T}: Add {W}.
You may untap Sunrise Prairie during each other player's untap step. Whenever you do, you lose 1 life.

Sunrise River enters tapped.
{T}: Add {U}.
You may untap Sunrise River during each other player's untap step. Whenever you do, you lose 1 life.

Sunrise Ruins enters tapped.
{T}: Add {B}.
You may untap Sunrise Ruins during each other player's untap step. Whenever you do, you lose 1 life.

Sunrise Woods enters tapped.
{T}: Add {G}.
You may untap Sunrise Woods during each other player's untap step. Whenever you do, you lose 1 life.

When Sunset Monastery enters, draw a card, then put a card from your hand on the bottom of your library.
{T}: Add {C}.

{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.