msem-instigator

{T}: Add {C}.
{T}, Pay 1 life: Add {R} or {W}.

{T}: Add {C}. If Soaring Observatory entered the battlefield this turn, add one mana of any color instead.
Tap three differently named untapped Academies you control: Add three mana in any combination of colors.

({T}: Add {G} or {U}.)
Soaring Rainforest enters the battlefield tapped.
{1}, {T}: Add {G}{G} or {U}{U}.

({T}: Add {U} or {B}.)
Sodden Cavern enters the battlefield tapped.

Lifelink
When you attain Sojourner of the Beyond, create two 1/1 white Spirit creature tokens with flying. They gain haste until end of turn.

{T}: Add {C}.
Satrapies you control have “{1}{W}, {T}, Exile a card from your graveyard: Create a 1/1 white Soldier creature token.”

Soli Sanctuary enters the battlefield tapped.
Satrapies you control have “{T}: Add {W} or {U}.”

Soli Temple enters the battlefield tapped.
Satrapies you control have “{T}: Add {G} or {W}.”

({T}: Add {B} or {G}.)
Somber Marsh enters the battlefield tapped.

Somber Meadow enters the battlefield tapped.
{T}: Add {W} or {B}.
{1}, {T}: Add one mana of any color.

Whenever equipped creature attacks or blocks, you gain 2 life.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

{T}: Add {C}.
{T}: Add one mana of any color among planeswalkers you control.
{1}, {T}: Put a loyalty counter on target planeswalker that activated a loyalty ability this turn.

Sparring Ground enters the battlefield with a +1/+1 counter on it.
{T}: Add {C}.
Whenever a creature enters the battlefield under your control, you may move a +1/+1 counter from Sparring Ground onto that creature.

Spawning Barrens enters the battlefield tapped unless you have 15 or less life.
{T}: Add {B} or {R}.

Creatures your opponents control can't block alone. (They can block different creatures.)

Spined Spire enters the battlefield tapped.
{T}: Add {U} or {R}.
{1}{U}{R}: Until end of turn, Spined Spire becomes a Lizard creature with menace in addition to its other types.
Scavenge {1}{U}{R}

Spinerock Canyon enters the battlefield tapped unless you control a basic land.
{T}: Add {R} or {W}.

Spiny Ridge enters the battlefield tapped. When it does, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this, then you may put that card into your graveyard.)
{T}: Add {R}.
{4}{R}: Spiny Ridge becomes a Lizard creature. (This effect lasts indefinitely.)

({T}: Add {R} or {W}.)
Spiraling Canyon enters the battlefield tapped unless you control a basic Mountain or a basic Plains.

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

Spired Canopy enters the battlefield tapped unless another player controls a land that could produce {G} or {U}.
{T}: Add {G} or {U}.

Spires of Caulte enters the battlefield tapped.
{T}: Add {B} or {R}.
{B}{R}: Until end of turn, Spires of Caulte becomes a 3/2 black and red Construct creature with with menace 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.)

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

{T}: Add {C}.
{T}: Add one mana of any color among creatures you control.
{X}: Spirit Blossom Shrine becomes an X/X Spirit creature until end of turn. It's still a land. Activate only if you control a creature with power X.

Splendid Scenery enters the battlefield tapped unless you control a basic land.
{T}: Add {G} or {W}.