msem-instigator

Until end of turn, if a source you don't control would deal damage to you or cause you to lose life, mill that many cards instead.

Create a 3/3 black Demon Horror creature token.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Equipped creature gets +1/+0 for each artifact you control.
Equip—Sacrifice an artifact.

({T}: Add {U} or {R}.)
Steamlit Peaks enters tapped.
{1}, {T}: Add {U}{U} or {R}{R}.

Flying
Whenever a player shuffles their library, Steamquiver Strix deals 2 damage to that player.

Flying
Other creatures you control with flying get +2/+2.

Vigilance
Renown 2 (When this creature deals combat damage to a player, if it isn't renowned, put two +1/+1 counters on it and it becomes renowned.)
{T}: Prevent the next X damage that would be dealt to target creature this turn, where X is Steelclad Investigator's power.

Flying
Vanguard — Whenever a creature you control attacks alone, you may put a +1/+1 counter on it.

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Whenever Steelhoof Battlechief attacks, another target attacking creature you control gets +2/+2 and gains trample until end of turn.

When Steward of Empire's Cradle enters, you may search your library for a Discovery, Quest, or Saga card, reveal it, then shuffle and put that card on top.
Civilized — If an ability of an enchantment you control triggers, if you control an artifact, a creature and an enchantment, that ability triggers an additional time.

You may reveal the second card you draw each turn as you draw it. When you do, create a 2/2 blue Avatar Wizard creature token with prowess if it's a creature card. If it's a land card, create a Treasure token. If it's a noncreature, nonland card, Steward of Second Sphere can't be blocked this turn.
{3}{W/U}{W/U}: Scry 2.

Target opponent discards a card at random. If that card's mana value is 3 or less, you may cast it without paying its mana cost.

When Stiff Butler enters, search target player's library for up to two cards and exile them. Then that player shuffles.

({T}: Add {W} or {U}.)
Still Waters enters tapped unless you control two or more basic lands.

Counter target noncreature spell. Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

When Still-Smoke Skirmisher dies, each opponent loses 1 life and you gain 1 life. Then return Still-Smoke Skirmisher to the battlefield at the beginning of the next end step if it was sacrificed.

When Still-Smoke Sojourners enters, remove all counters from target player or permanent. That player or that permanent's controller loses life equal to the number of counters removed this way.

Creature cards in your graveyard have revive. The revive cost is equal to their mana cost. (Pay that creature's mana cost, Exile that card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

When Stillmarsh Brinecatcher enters, return another target nonland permanent to its owner's hand.
At the beginning of your end step, if you control a permanent with mana value 5 or greater, you may sacrifice Stillmarsh Brinecatcher. If you do, draw a card and create a 3/2 colorless Horror creature token.

If you would draw a card, you may skip that draw. If you do, create a tapped Treasure token and exile the top card of your library. You may play that card this turn.

Deathtouch
Whenever you cast a spell, you may pay 2 life. If you do, that spell gains deathtouch. (If it becomes a permanent, it keeps deathtouch indefinitely.)

Stinging Swordfish has first strike as long as it's attacking.
When Stinging Swordfish dies, create an Equipment enchantment artifact token named Fish Sword with “Equipped creature gets +3/+1,” “Equipped creature has first strike as long as it's attacking,” and equip {2}. You may attach that token to a creature you control.

When Stolen Innovations enters, target opponent reveals their hand. You choose an instant or sorcery card from that player's hand or graveyard and exile it.
You may cast each spell you cast from your hand as a copy of the exiled card. You may spend mana as though it were mana of any color to cast spells this way.

When Stolen Light enters, exile target nonland permanent an opponent controls until Stolen Light leaves the battlefield.
{W}{U}{B}{R}{G}: Put a permanent card exiled with Stolen Light onto the battlefield under your control. It's a 3/3 Horror creature in addition to its other types.

Take an extra turn after this one. At the beginning of that turn's upkeep, if you control a legendary creature, each opponent exiles the top card of their library. Until the end of that turn, you may play those cards and you may spend mana as though it were mana of any type to cast those spells.
Exile Stolen Moments.