msem-instigator

Flying
Whenever you cast a creature spell, if Script Spirit is in your graveyard, you may have it become a copy of that spell until end of turn.

When Scrollmaster dies, you may exile it. If you do, search your library for an instant or sorcery card with mana value 4 or less and cast it without paying its mana cost. If you searched your library this way, shuffle.

Scrounging Dunes enters tapped.
{T}: Add {W} or {B}.
{1}{W}{B}: Until end of turn, Scrounging Dunes becomes a Wurm creature with lifelink in addition to its other types.
Scavenge {1}{W}{B}

At the beginning of your upkeep, you lose 1 life, then audition for black. (Create a 1/1 Construct Actor creature token, a Cleric Role giving 2/2 and lifelink, or a Warlock Role giving 2/1 and flying. Roles replace older ones.)

At the beginning of combat on your turn, if you cast both a creature spell and a noncreature spell this turn, untap up to one target land you control. It becomes a 3/1 red Sand creature with haste in addition to its other types until end of turn.

Flash
When Scuripi Lookout enters, target creature gains hexproof until end of turn.
Whenever one or more creatures you control attack, you may return Scuripi Lookout to its owner's hand.

At the beginning of your upkeep, if six or more cards are in your graveyard, you may transform Scuttling Gnat.

Draw a card, then draw cards equal to the number of cards named Sea Cache in your graveyard.

Play with the top card of your library revealed.
You may cast Elemental spells from the top of your library.

Sea Of Skies Beyond enters tapped.
Whenever you cast a noncreature spell, put a creation counter on Sea Of Skies Beyond.
{T}, Remove ten creation counters from Sea Of Skies Beyond and sacrifice it: Shuffle your hand into your library, then draw five cards.

This spell costs {2} less to cast for each creature that died this turn.
Each player exiles all creature cards from their graveyard, then sacrifices each creature they control, then puts all creature cards they own exiled this way onto the battlefield. Exile Sea of Corpses.

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
When Sea's Allure enters, gain control of target creature for as long Sea's Allure remains on the battlefield.

Menace (This creature can't be blocked except by two or more creatures.)
Whenever another creature dies, you may salvage a creature card. (Exile one from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

Flash
When Seabreen Nullmage enters, counter target activated or triggered ability. (A triggered ability uses the words “when,” “whenever,” or “at”. Mana abilities can't be targeted.)

Concord — {1}{G}: Until end of turn, Seadrake Rider gets +2/+3 and must be blocked if able. Activate only during your turn, only once each turn, and only if there are four or more card types among permanents you control.

Flash
{U}, Sacrifice Seal of Approval: Counter target spell unless its controller pays {2}.

Choose target card in a graveyard other than a basic land card. Search its owner's graveyard, hand, and library for any number of cards with the same name as that card and exile them. Then that player shuffles.
Scry 1.

{T}: Add {C}.
{T}, Tap an untapped artifact, creature, or land you control: Add one mana of any color.
{T}: Choose a card name, then reveal the top card of your library. If that card has the chosen name, you may sacrifice Sealed Archives and draw a card.

Cards in graveyards lose all abilities.
Cards in graveyards can't be the target of spells or abilities.

When Sealed Riftway enters, exile up to one target card from a graveyard.
{2}, {T}, Sacrifice Sealed Riftway: Exile target player's graveyard. Draw a card.

Trample
When Sealer of Pacts enters, sacrifice any number of permanents, then draw that many cards.

Sear Flesh deals 3 damage to target creature or planeswalker. If you've cast another spell this turn, it deals 5 damage instead.

When Sear, Forged of Lava enters, create a 3/3 red Panda creature token, then attach it to that token.
Equipped creature gets +3/+3, has flying, haste, and “Whenever this creature dies, it deals 3 damage to target opponent or planeswalker.”
Equip {2}{R}{R}

Return target cryptic card from your graveyard to your hand. (Artifacts, enchantments, and modal spells are cryptic.)

Whenever Search the Shadows or a nontoken Ninja or Rogue you control enters, create a 1/1 blue Ninja creature token with “This creature can't be blocked.”
Whenever one or more Ninja and/or Rogue creatures you control deal combat damage to a player, draw a card.