msem-instigator

{T}: Add {C}.
{T}, Exile two cards from your graveyard: Add {U} or {R}.

Stormcharged Pyre enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

Other artifacts you control have ward {1}.
Overcast — Whenever you cast an artifact creature spell, if {C} was spent to cast it, it enters with an additional +1/+1 counter on it.

Strange Harbor enters tapped unless you have 15 or less life.
{T}: Add {U} or {R}.

Prowess
Pay 2 life: Change a target of target spell or ability to Straw Intellectual.

Creatures blocking or blocked by Straw Officer have wither. (They deal damage to creatures in the form of -1/-1 counters.)

As Straw Simulacrum enters, choose a creature type.
Straw Simulacrum is the chosen creature type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Equipped creature gets +1/+1 and has haste.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Stunning Cascade enters tapped.
{T}: Add {U} or {R}.
{2}{U}{R}, {T}, Sacrifice Stunning Cascade: Draw a card.

As Sturdy Outpost enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {G}, {W}, or {U}.

({T}: Add {B}.)
As Stygian Dunes enters, you may pay 1 life. If you don't, Stygian Dunes enters tapped.

Substack Ports enters tapped.
{T}: Add {U} or {B}.
{U}{B}, {T}, Sacrifice Substack Ports: Conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

[+1]: Each opponent loses 1 life for each card you've drawn this turn. Then you draw a card.
[–2]: Shi Hou, the Sun King deals 2 damage to target creature or planeswalker and you gain 2 life. If that permanent was already dealt damage this turn, destroy it.

Sundappled Scrub enters tapped unless you control another Desert.
{T}: Add {G} or {W}.

Equipped creature gets +1/+0 and gains “Whenever this creature deals damage to a player or planeswalker, you may draw two cards. If you do, discard a card.”
Equip {2}

{1}, {T}: End the turn. Activate only during your turn.

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

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

Sunken Cavern enters tapped unless another player controls a land that could produce {U} or {R}.
{T}: Add {U} or {R}.

When Sunken Grave enters, create a tapped 2/2 black Zombie creature token.
{5}, {T}, Sacrifice Sunken Grave: Create a tapped 2/2 black Zombie creature token.

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.

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}.

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}.”