msem-instigator

This spell costs {1} less to cast for each creature you control that attacked this turn.
First strike
Whenever Weavetide Militia and at least one other creature attack, creatures you control get +1/+0 until end of turn.

When this creature enters, if you cast it, return target permanent card with mana value 3 or less from your graveyard to the battlefield tapped.
Whenever this creature attacks, you may sacrifice a nonland permanent. If you do, it gets +1/+1 and gains indestructible until end of turn.

When Daughter of Calenfyr enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.
When Daughter of Calenfyr dies, you may put a land card from your hand onto the battlefield tapped.

Whenever equipped creature attacks, put a charge counter on Shimmersting, then create a token that's a copy of equipped creature and that's tapped and attacking for each charge counter on Shimmersting, except the tokens aren't legendary. Exile the tokens at the beginning of the end step.
Equip {5}

Destroy target creature or planeswalker you don't control. Its controller creates two tapped Treasure tokens.

Advance {3}{R}{R} (Cast this for {3}{R}{R} to advance it as it enters. {3}{R}{R}: Advance this as a sorcery.)
Flying, haste
Whenever Skiviar Scraplord advances, put a +1/+1 counter on it.

Death knell — You may sacrifice a nontoken creature. If you do, create a 3/3 black Spirit creature token. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)
Creatures you control dying causes their death knell to trigger. (In addition to the normal death knell trigger.)

Destroy target creature or planeswalker. That permanent's controller loses 3 life unless that player sacrifices a nonland permanent or discards a card.

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
When Cuff Down enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

When Hall of Remembrance enters, create two 1/1 white Spirit creature tokens with flying.
Whenever a Spirit you control enters, you gain 1 life.

Flash
When Lizaveth's Surveyor enters, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Lizaveth's Surveyor's power is equal to the number of artifacts you control.

Whenever you cast an enchantment spell, create a 1/1 white and black Bird creature token with flying and vigilance.
Whenever three or more creatures you control deal combat damage to a player, that player sacrifices a creature. If they can't, they discard a card.

Whenever a creature you control becomes blocked, you may return it to its owner's hand.
The first spell you cast during your postcombat main phase each turn costs {W}{U} less to cast. This effect reduces only the amount of colored mana you pay. (For example, if you cast a spell with mana cost {1}{U}, it costs {1} to cast.)

Whenever you scry, tap target creature an opponent controls.
{2}{W}{U}: Scry 1. You gain 1 life.

When Diviner of the Mists enters, target opponent chooses two cards in their hand and reveals one of them. Exile one of those cards. You may play that card for as long as it remains exiled, and spend mana as though it were mana of any color to cast it.

Flying
As long as you control an equipped creature, Guide of Heroes gets +1/+1 and has first strike.
As long as you control an enchanted creature, Guide of Heroes gets +1/+1 and has vigilance.

Core Ignition deals X damage to target creature or planeswalker.
Conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

Put target attacking or blocking creature on top of its owner's library.
Fuse (You may cast one or both halves of this card from your hand.)

Flying
Whenever Sinewed Wings deals combat damage to a player, you may discard your hand. If you do, draw a card for each creature with flying you control.

Return target creature card from your graveyard to the battlefield.
Fuse (You may cast one or both halves of this card from your hand.)

Exile target artifact or enchantment with mana value 4 or less.

Flying
{T}: Target attacking creature gets +1/+1 and gains flying until end of turn.

({T}: Add {W}.)
Bustling Docks enters tapped.
{W}, {T}, Reveal a white card from your hand: Target creature gets +1/+0 until end of turn.

When Godwatcher enters, search any player's library for a creature card, exile it, then they shuffle their library.
When Godwatcher dies, put the exiled card onto the battlefield under your control.

Destroy target creature if it has the least power or is tied for least power among creatures on the battlefield.
Memento {3}{B}{B} (You may cast this from your graveyard for {3}{B}{B}. If you do, put it onto the battlefield transformed after it resolves. Exile it if it would leave the battlefield or not resolve.)