msem-instigator

Savage Lands enters the battlefield tapped.
{T}: Add {B}, {R}, or {G}.

({T}: Add {G}.)
Savage Sanctuary enters the battlefield tapped with two sanctum counters on it.
{T}, Remove a sanctum counter from Savage Sanctuary: Add {R} or {W}.

(Transform this if it's not attached to a creature. Pay {1}{R} as a sorcery to unattach it.)
Enchant creature you control
Scale Bearer's rider gets +4/+3 and has flying and haste.
Whenever Scale Bearer's rider attacks, you may pay {2}{R}. If you do, it deals damage equal to its power to target creature or planeswalker.

Whenever Scaleblight Cutthroat attacks, each opponent loses life equal to its power.
{4}{B}{B}: Scaleblight Cutthroat gets +3/+3 until end of turn.

Enchant player
Whenever enchanted player taps a nonbasic land they control, that land doesn't untap during its controller's next untap step.

Scavenger Holdout enters the battlefield tapped.
When Scavenger Holdout enters the battlefield, you may pay {3}. If you do, create two 1/1 green Scout creature tokens.
{T}: Add {C}.

As Scorched Copse enters the battlefield, you may tap an untapped creature you control. If you don't, Scorched Copse enters the battlefield tapped.
{T}: Add {R} or {G}.

Scoured Barrens enters the battlefield tapped.
When Scoured Barrens enters the battlefield, you gain 1 life.
{T}: Add {W} or {B}.

Scoured Mesa enters the battlefield tapped.
{T}: Add {W}.
Desertcycling {1}{W} ({1}{W}, Discard this card: Search your library for a Desert card, reveal it, and put it into your hand, then shuffle.)

Double strike
Creatures you control have trample.
Excess noncombat damage that would be dealt by sources you control to permanents an opponent controls is dealt to that player instead.

Scrounging Dunes enters the battlefield tapped.
{T}: Add {W} or {B}.
{1}{W}{B}: Until end of turn, Scrounging Dunes becomes a Wurm creature with lifelink in addition to its other types.
Scavenge {1}{W}{B}

Sculpted Observatory enters the battlefield tapped.
{T}: Add {W} or {U}.
{1}, {T}: Add one mana of any color.

Sea Of Skies Beyond enters the battlefield tapped.
Whenever you cast a noncreature spell, put a creation counter on Sea Of Skies Beyond.
{T}, Remove ten creation counters from Sea Of Skies Beyond and sacrifice it: Shuffle your hand into your library, then draw five cards.

Seaside Citadel enters the battlefield tapped.
{T}: Add {G}, {W}, or {U}.

({T}: Add {U}.)
As Seaside Grotto enters the battlefield, you may pay 1 life. If you don't, Seaside Grotto enters the battlefield tapped.
Basic lands you control have “{T}: Add {U}.”

({T}: Add {G} or {U}.)
Secluded Cascade enters the battlefield tapped unless you control two or more basic lands.

As Secluded Courtyard enters the battlefield, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type or activate an ability of a creature source of the chosen type.

{T}: Add {C}.
{T}, Reappropriate: Add {G} or {W}. (Exile exactly two cards from your hand and/or graveyard.)

({T}: Add {W} or {U}.)
Whenever Sedate Tundra becomes tapped, you lose 1 life unless you control two or more basic lands.

({T}: Add {G}.)
Seedshrine enters the battlefield tapped.
When Seedshrine enters the battlefield, you may put a +1/+1 counter on target creature.

{T}, Pay 1 life: Add {B} or {G}.
{1}, {T}, Sacrifice Seedy Bar: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Creatures with power less than Seer of the Hunt's power can't block it.

Whenever you scry, draw a card.

{T}: Add {C}.
{7}, {T}: Create a 2/2 colorless Spirit creature token.

{T}: Add {C}.
{T}, Reappropriate: Add {U} or {B}. (Exile exactly two cards from your hand and/or graveyard.)