msem-instigator

Players can't sacrifice creatures to cast spells or activate abilities unless that player sacrifices an additional creature. The same is true for discarding cards and paying life.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Master of Ancient Ways mentors a creature, that creature gains double strike until end of turn.

Embellish {4}{W} (If you cast this spell for {4}{W}, create a 1/1 blue Thopter artifact creature token with flying when it enters.)
When Meticulous Mechanist enters, scry 1.

When Militia Commander enters, create a 1/1 white Peasant creature token.
Other Citizens and Peasants you control get +1/+1.

When Militia Surgeon enters, you gain 2 life.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

First strike
Other Harpies you control get +1/+1 and have first strike.
Whenever a Harpy you control dies, put a +1/+1 counter on Moonlight Stalker.

When Mythos Scribe enters, you may return target storied card from your graveyard to your hand. (Enchantments and legendary permanents are storied.)

Oreskos Warden has lifelink as long as you control an enchantment.

Vigilance
When Paired Pathfinders enters, if three or more colors were spent to cast it, create a 1/1 colorless Servo artifact creature token.

Whenever Patron of Asham attacks, tap target creature an opponent controls with power less than or equal to your fealty to Plains. (Each Plains you control counts towards your fealty to Plains.)

Whenever an enchantment you control enters, create a 1/1 colorless Construct Actor creature token.
Token creatures you control have vigilance.

Lifelink
Whenever another creature you control with a counter on it dies, return it to its owner's hand. If that creature was an Avatar, return it to the battlefield under your control instead.

First strike
Creatures you control attacking cause abilities of that creature to trigger as though it entered.

First strike
Engage (This creature must be blocked each combat if able.)

Spells you cast that target Risti Operative cost {1} less to cast.
Abilities you activate that target Risti Operative cost {1} less to activate.

When Rotting Sunseeker dies, return target creature card with power 2 or less from your graveyard to your hand.

Vigilance
When Roya Ritualist enters or whenever you cast a spell, if {G}{U} was spent to cast it, draw a card, then you may put a land card from your hand onto the battlefield tapped. Put a +1/+1 counter on Roya Ritualist.

Ward {2}
Foresight — Whenever you draw your second card each turn, Royal Falconer gains flying until end of turn.

Whenever you cast a cryptic spell, creatures you control get +1/+1 until end of turn. (Artifacts, enchantments, and modal spells are cryptic.)

When Russet Denmother enters, choose one —
• Destroy target enchantment.
• Create a 2/1 red and white Fox creature token.

When Sandbluff Barflies enters, you gain 2 life.

When Seikatsu Warleader enters, if it's not a token, create a token that's a copy of target creature token you control.

Whenever a land you control enters, you may tap target creature.

First strike