Snake Pit

Whenever an opponent casts a blue or black spell, you may create a 1/1 green Snake creature token.

Spirit Mirror

At the beginning of your upkeep, if there are no Reflection tokens on the battlefield, create a 2/2 white Reflection creature token.
{0}: Destroy target Reflection.

Song of Serenity

Creatures that are enchanted can't attack or block.

Snowfall

Cumulative upkeep {U} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an Island is tapped for mana, its controller may add an additional {U}. If that Island is snow, its controller may add an additional {U}{U} instead. Spend this mana only to pay cumulative upkeep costs.

Smoke

Players can't untap more than one creature during their untap steps.

Pattern of Rebirth

Enchant creature
When enchanted creature dies, that creature's controller may search their library for a creature card, put that card onto the battlefield, then shuffle.

Shivan Harvest

{1}{R}, Sacrifice a creature: Destroy target nonbasic land.

One with Nature

Enchant creature
Whenever enchanted creature deals combat damage to a player, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Soul Exchange

As an additional cost to cast this spell, exile a creature you control.
Return target creature card from your graveyard to the battlefield. Put a +2/+2 counter on that creature if the exiled creature was a Thrull.

Spelljack

Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard. You may play it without paying its mana cost for as long as it remains exiled. (If it has X in its mana cost, X is 0.)

Spirit of Resistance

As long as you control a permanent of each color, prevent all damage that would be dealt to you.

Sigil of Sleep

Enchant creature
Whenever enchanted creature deals damage to a player, return target creature that player controls to its owner's hand.

Orim's Thunder

Kicker {R} (You may pay an additional {R} as you cast this spell.)
Destroy target artifact or enchantment. If this spell was kicked, it deals damage equal to that permanent's mana value to target creature.

Soltari Visionary

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever Soltari Visionary deals damage to a player, destroy target enchantment that player controls.

Soldevi Adnate

{T}, Sacrifice a black or artifact creature: Add an amount of {B} equal to the sacrificed creature's mana value.

Parallax Tide

Fading 5 (This enchantment enters with five fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from Parallax Tide: Exile target land.
When Parallax Tide leaves the battlefield, each player returns to the battlefield all cards they own exiled with Parallax Tide.

Overburden

Whenever a player puts a nontoken creature onto the battlefield, that player returns a land they control to its owner's hand.

Rishadan Pawnshop

{2}, {T}: Shuffle target nontoken permanent you control into its owner's library.

Spoils of Evil

For each artifact or creature card in target opponent's graveyard, add {C} and you gain 1 life.

Songs of the Damned

Add {B} for each creature card in your graveyard.

Sphere of Law

If a red source would deal damage to you, prevent 2 of that damage.

Rupture

Sacrifice a creature. Rupture deals damage equal to that creature's power to each creature without flying and each player.

Oubliette

When Oubliette enters, target creature phases out until Oubliette leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)

Paradigm Shift

Exile all cards from your library. Then shuffle your graveyard into your library.

Ritual of the Machine

As an additional cost to cast this spell, sacrifice a creature.
Gain control of target nonartifact, nonblack creature.

Sphinx of Enlightenment

Flying
When Sphinx of Enlightenment enters, target opponent draws a card and you draw three cards.

Serene Master

Whenever Serene Master blocks, exchange its power and the power of target creature it's blocking until end of combat.

Parallel Thoughts

When Parallel Thoughts enters, search your library for seven cards, exile them in a face-down pile, and shuffle that pile. Then shuffle your library.
If you would draw a card, you may instead put the top card of the pile you exiled into your hand.

Scalding Salamander

Whenever Scalding Salamander attacks, you may have it deal 1 damage to each creature without flying defending player controls.

Peacekeeper

At the beginning of your upkeep, sacrifice Peacekeeper unless you pay {1}{W}.
Creatures can't attack.

Shimmer

As Shimmer enters, choose a land type.
Each land of the chosen type has phasing. (It phases in or out before its controller untaps during each of their untap steps. While it's phased out, it's treated as though it doesn't exist.)

Steal Enchantment

Enchant enchantment
You control enchanted enchantment.

Soul Barrier

Whenever an opponent casts a creature spell, Soul Barrier deals 2 damage to that player unless they pay {2}.

Parallax Wave

Fading 5 (This enchantment enters with five fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from Parallax Wave: Exile target creature.
When Parallax Wave leaves the battlefield, each player returns to the battlefield all cards they own exiled with Parallax Wave.

Orcish Lumberjack

{T}, Sacrifice a Forest: Add three mana in any combination of {R} and/or {G}.

Orcish Squatters

Whenever Orcish Squatters attacks and isn't blocked, you may gain control of target land defending player controls for as long as you control Orcish Squatters. If you do, Orcish Squatters assigns no combat damage this turn.

Spreading Plague

Whenever a creature enters, destroy all other creatures that share a color with it. They can't be regenerated.

Pendrell Mists

All creatures have "At the beginning of your upkeep, sacrifice this creature unless you pay {1}."

Mangara's Tome

When Mangara's Tome enters, search your library for five cards, exile them in a face-down pile, and shuffle that pile. Then shuffle your library.
{2}: The next time you would draw a card this turn, instead put the top card of the exiled pile into its owner's hand.

Reap

Return up to X target cards from your graveyard to your hand, where X is the number of black permanents target opponent controls as you cast this spell.

Phantasmal Mount

Flying
{T}: Target creature you control with toughness 2 or less gets +1/+1 and gains flying until end of turn. When Phantasmal Mount leaves the battlefield this turn, sacrifice that creature. When the creature leaves the battlefield this turn, sacrifice Phantasmal Mount.

Reality Ripple

Target artifact, creature, or land phases out. (While it's phased out, it's treated as though it doesn't exist. It phases in before its controller untaps during their next untap step.)

Skyshroud War Beast

Trample
As Skyshroud War Beast enters, choose an opponent.
Skyshroud War Beast's power and toughness are each equal to the number of nonbasic lands the chosen player controls.

Soul Sculptor

{1}{W}, {T}: Target creature becomes an enchantment and loses all abilities until a player casts a creature spell.

Slaughter

Buyback—Pay 4 life. (You may pay 4 life in addition to any other costs as you cast this spell. If you do, put this card into your hand as it resolves.)
Destroy target nonblack creature. It can't be regenerated.

Reconnaissance

{0}: Remove target attacking creature you control from combat and untap it. (If you activate during end of combat, the creature will untap after it deals combat damage.)