msem-instigator

When Scrapyard Aberration enters, you may sacrifice another artifact. If you do, target creature gets -2/-2 until end of turn.

Sacrifice Scrapyard Raiders: Target artifact gains indestructible until end of turn.

Flying
Whenever an artifact you control enters, you may activate one of its activated abilities without paying its cost.

When Screams from the Deep enters, exile up to one target monocolored permanent.
As long as an opponent owns three or more cards in exile, you may have Screams from the Deep assign its combat damage as though it weren't blocked.
Evoke {5} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

{3}{B}, Exile Screeching Duneborn from your graveyard: You gain 1 life and draw a card.

Counter target permanent spell. (Then exile this card. You may cast the creature later from exile.)

When Scribal Puppeteer enters, create two 1/1 black Puppet creature tokens with “At the beginning of your upkeep, you lose 1 life.”

Trample, prowess

Ward {2}
Once each turn, if you would create one or more tokens, create that many of those tokens plus one instead.

Whenever you cast an instant or sorcery spell, put a +1/+1 counter on Scribe of the Sky Scrolls. If you spent four or more mana to cast that spell, Scribe of the Sky Scrolls gains flying until end of turn.

Whenever you cast a spell with mana value greater than Script Jockey's power, put a +1/+1 counter on Script Jockey.

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.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create two 1/1 white Human creature tokens.
II — Put a vigilance counter on target creature you control. It becomes a legendary God in addition to its other types.
III — Exile target creature an opponent controls that's a God or that has power 4 or greater.

When Scrivener of Sha'Iv enters, draw a card and adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)

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.

Scrollsnatcher can't block and can't be blocked.
Whenever Scrollsnatcher deals combat damage to a player, look at the top card of each library, then put any number of those cards into their owner's graveyards.

Haste
Frenzy 2 (Whenever this creature attacks and isn't blocked, it gets +2/+0 until end of turn.)

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}

When Scrying Pool enters, scry 2.
{1}, {T}: Add one mana of any color.

{2}{B}, {T}, Sacrifice Sculler's Oar: Return up to two target creature cards from your graveyard to your hand.

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.)

Sculpted Observatory enters tapped.
{T}: Add {W} or {U}.
{1}, {T}: Add one mana of any color.

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.

Enchant creature
Enchanted creature gets +2/+2.
Enchanted creature has hexproof as long as it's tapped.

When Scuripi Collector enters, return target artifact, enchantment, or land card from your graveyard to your hand.