msem-instigator

When Spellbound Gauntlet enters, put a +1/+1 counter on target creature you control.
{T}: Add one mana of any color.

When Spellslinger's Gauntlet enters, exile an instant or sorcery card with mana value 3 or less from your hand.
Whenever equipped creature attacks, you may copy the exiled card. If you do, you may cast the copy without paying its mana cost.
Equip {3}

Defender, flying
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)
Remove a +1/+1 counter from Spellwork Bulwark: It loses defender and gains hexproof and indestructible until end of turn.

{1}, {T}, Exile Sphere of Sorcery: Return target noncreature, nonland card from your graveyard to your hand.
{8}, {T}, Exile Sphere of Sorcery: Return any number of target noncreature, nonland cards from your graveyard to your hand.

Spined Spire enters 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}

When Spinegraft Disabler enters, exile target creature until Spinegraft Disabler leaves the battlefield.

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

Haste
Ward—Sacrifice a creature.
Spinning Gears Abomination enters with X +1/+1 counters on it.
Spinning Gears Abomination can't attack alone.

Spiny Ridge enters 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 tapped unless you control a basic Mountain or a basic Plains.

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

{T}: Add {G}, {W}, or {U}.
Cycling {2} ({2}, Discard this card: Draw a card.)

{T}: Add {W}, {U} or {B}.
Cycling {2} ({2}, Discard this card: Draw a card.)

{T}: Add {U}, {B}, or {R}.
Cycling {2} ({2}, Discard this card: Draw a card.)

{T}: Add {B}, {R}, or {G}.
Cycling {2} ({2}, Discard this card: Draw a card.)

{T}: Add {R}, {G}, or {W}.
Cycling {2} ({2}, Discard this card: Draw a card.)

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

Spires of Caulte enters 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.

Whenever you cast a noncreature spell, you gain 1 life.

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

When Splinter of Creation enters, you may exile any number of land cards from your graveyard.
You may play lands exiled with Splinter of Creation.

{T}: Add {C}.
{4}, {T}: Create a 0/1 white Goat creature token.
{T}, Sacrifice X Goats: Add X mana of any one color. You gain X life.

Equipped creature has “You may choose not to untap this creature during your untap step” and “{T}: Gain control of target creature with power 5 or greater for as long as you control this creature and it remains tapped.”
Equip {3}