msem-instigator

Target player mills a card. Create a 3/2 colorless Horror creature token. Put a decayed counter on it. (It can't block. When it attacks, sacrifice it at end of combat.)

When Blisterbug dies, put two +1/+1 counters on target creature you control.

Target player sacrifices a creature or planeswalker.
Leitmotif (If you cast this spell from your hand, exile it as it resolves. When you next cast a spell that shares a color with this card, you may cast this from exile without paying its mana cost.)

Whenever Practical Battlemage attacks, catalyze. (The next spell you cast this turn costs {1} less to cast.)

Whenever Dauntless Qith becomes the target of a spell or ability, Dauntless Qith gains double strike until end of turn.

As an additional cost to cast this spell, discard a card or pay {4}.
Destroy target creature.

[+1]: Return up to one target Aura card from a graveyard or on the battlefield to its owner's hand.
[–2]: Sacrifice an enchantment. If you do, return target enchantment card from your graveyard to the battlefield.
[–6]: Draw three cards. Until end of turn, you may cast enchantment spells without paying their mana costs.

Whenever a creature you control deals combat damage to a player, if it has no +1/+1 counters on it, put a +1/+1 counter on it. You gain 1 life.

When Humored Outlaw enters, choose one —
• Put a +1/+1 counter on Humored Outlaw. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)
• Destroy target artifact or enchantment.

Whenever High-Priestess Nebti attacks or blocks, create a 2/2 white Cat creature token.
{1}{R}{R}, Tap an untapped Cat creature you control: That creature fights target creature you don't control.

Flash
When Rahstahde Truthseeker enters, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Return X target cards with different mana costs from your graveyard to your hand. Exile Eternal Blessings.

Deathtouch
Menagerie — When Sting-Hopper enters, if there are five or more creature types among creatures you control, target player reveals their hand. You choose a creature card from it. That player discards that card.

Motivate 3 (When this creature enters, you may motivate target creature with less power than this by putting three +1/+1 counters on it.)
When General Merthilios motivates a creature, that creature gains first strike, trample, and haste until end of turn.

[+1]: Create a 1/1 blue Dragon creature token with flying and “This creature can't attack unless you control a nontoken Dragon.”
[–2]: Flynn deals damage to target creature or planeswalker equal to the total power of Dragons you control.
[–5]: You get an emblem with “Dragon spells you cast cost {U}{R} less to cast and have flash.”

Flying
Whenever a creature dealt damage by Subturgian Legionnaire this turn dies, create a 1/1 black Vampire creature token with lifelink.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{1}, Discard two cards: Unlock Cryptic Fragment. If the revealed card is a basic land card, put it into your hand.

Defender
Whenever you cast an enchantment, instant, or sorcery spell, scry 1 if it's the first time this ability has resolved this turn. If it's the second time, Prismscale Piranhas can attack this turn as though it didn't have defender. If it's the third time, whenever Prismscale Piranhas deals combat damage to a player this turn, draw a card.

When Karoa's Faithful enters, target creature gets +X/+X until end of turn, where X is the total number of creatures you control that are Knights or have Adventures.

{2}{B}, Sacrifice a creature: Draw a card. You gain 1 life.

Double strike
Art of war — At the beginning of your end step, if Kogane's Swordmaster dealt damage to an opponent this turn, put a +1/+1 counter on it.

Advance {4}{B}{B} (Cast this for {4}{B}{B} to advance it as it enters. {4}{B}{B}: Advance this as a sorcery.)
Flying
Whenever Valinov Siphoner advances, target player loses 2 life and you gain 2 life.

Search your library for a basic land card and put it onto the battlefield, then shuffle.
Orchestrate {1}{G} (You may exile this card from your hand anytime you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

Target opponent may have The Highest Stakes deal 4 damage to them. If that player doesn't, you draw two cards.
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.”)

{T}: Add {R} or {G}.
{T}, Sacrifice Sigil of Savagery: Add {R}{G}.