msem-instigator

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}

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.

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

At the beginning of each player's upkeep, that player discards a card. If that player has no cards in hand, instead they sacrifice a permanent. If they control no permanents, instead they lose the game.

({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}.

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.

Draw two cards, then discard a card.
Whenever you cast an instant or sorcery spell, if Spirit Script is in your graveyard, you may have it become a copy of that spell until end of turn.

When Spirit of Autumn enters, nourish X, where X is the number of creatures you control. (To nourish X, either put X +1/+1 counters on this creature or create X 1/1 white Citizen creature tokens.)

Whenever Spirit of Infamy attacks, post a bounty on target creature. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)
Spirit of Infamy gets +2/+0 for each bounty counter on it.

Flying, deathtouch
Creatures that aren't Spirits or Warlocks get -1/-1.

Flying
Whenever Spirit of Vitriol attacks, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Discard a card: Spirit of Vitriol gains hexproof until end of turn. Tap it.

Flash
If an opponent would gain life or damage to a permanent or opponent would be prevented, instead Spirit-Lantern Incendiary deals 1 damage to that permanent or opponent.

Flying, lifelink
Skip your draw step.
Pay 3 life: Draw three cards. Activate only as a sorcery and only once each turn.

If an effect would create one or more tokens, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent, it puts twice that many of those counters on that permanent instead.

Destroy target artifact or enchantment. Spit on the Grave deals 2 damage to that permanent's controller.(Cast a copy of this spell once while this creature is on the battlefield.)

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.

Flying, haste
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
When Splitflame Phoenix dies, you may pay {R}. If you do, return it to its owner's hand.

Flash
When Splitting Image enters, you may pay {2} any number of times. Whenever you do, copy target spell. You may reselect modes and choose new targets for the copies.

At the beginning of your upkeep, each opponent mills two cards.
{3}{B}: Exile target nonland card from an opponent's graveyard. Copy it. You may cast the copy. Activate only as a sorcery. (You still pay its costs, including color. Copies of permanents enter as tokens.)

{1}{G}: Exile two target cards from a single graveyard. When you do, germinate. (Put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

Cast this spell only if an opponent controls a creature with power 5 or greater or you control six or more lands.
Return all nonland permanents target player controls to their owner's hand.