msem-instigator

{1}, {T}, Sacrifice Soul-Synthesizer: Look at the top seven cards of your library. You may reveal a card with an activated ability from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Activated abilities of cards in your graveyard cost {2} less to activate.

Activated abilities of cards in your hand cost up to {1} less to activate. This effect can't reduce the amount of mana an ability costs to activate to less than one mana.

{3}, {T}, Sacrifice a non-Spirit creature: Create a 1/1 white Spirit creature token with flying.

Whenever you cast a noncreature spell, you may put a progress counter on Sovereign Skies.
[PROGRESS 2+] Indestructible
{T}: Add {C}.
[PROGRESS 9+] Sovereign Skies is a 9/9 Ship artifact creature with flying.

{1}, Sacrifice Sovereign Stone: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
{1}, Sacrifice Sovereign Stone: Draw a card.

Equipped creature gets +3/+1 and has reach.
Equip {4}

Spare Supplies enters tapped.
When Spare Supplies enters, draw a card.
{2}, {T}, Sacrifice Spare Supplies: Draw a card.

{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.

{2}: Sparkline Dancer gains flying until end of turn.

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

Spawning Barrens enters 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.)

When Specialized Training Dummy enters, choose a card name.
Other creatures you control with the chosen name get +1/+1.

When Spellblade enters, you may exile an instant card with mana value 2 or less from your hand.
At the beginning of your end step, if equipped creature dealt damage to an opponent this turn, you may copy the exiled card. If you do, you may cast the copy without paying its mana cost.
Equip {2}

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}

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

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.)