msem-instigator

When Ill-Fated Seer enters, each player sacrifices a creature. If they can't, Ill-Fated Seer deals 3 damage to them.
Revive {2}{B}{R} ({2}{B}{R}, Exile this card from your graveyard: Create a token that's a copy of this card, except it has no mana cost. Activate only as a sorcery.)

First strike (This creature deals combat damage before creatures without first strike.)
Whenever a creature you control becomes blocked by a creature, Itava Scourge deals 1 damage to that creature's controller.

Menace
Discard a card: Target artifact creature you control salvages Rappel Liner. Activate only if Rappel Liner is in your graveyard and only as a sorcery. (Exile this card until that creature leaves the battlefield. When that creature deals combat damage to a player, return a card it salvaged to your hand.)

Whenever you cast a spell from your graveyard, you may sacrifice a creature. If you do, copy that spell. You may choose new targets for the copy.

Whenever Crescent Crasher attacks, put a +1/+1 counter on target attacking creature with lesser power.

Whenever you create one or more tokens, put a +1/+1 counter on target creature you control.
{2}{G}{W}: Create a 0/1 green Plant creature token.

If an enchanted permanent you control would leave the battlefield, instead destroy one of the Auras attached to it, then that permanent phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

At the beginning of your upkeep, invigorate 1. (Choose a creature with the least power among creatures you control and put a +1/+1 counter on it.)

When Overconfident Batter dies, if it's enchanted or you cast a spell that targeted it this turn, you gain 3 life.

Whenever you investigate for the first time each turn, investigate an additional time.
{T}, Sacrifice an artifact: Cadalon Inspector deals 2 damage to any target.

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Favoured Firebrand dies, you may pay {U}{R} any number of times. Whenever you do, Favoured Firebrand deals 2 damage to any target and you draw a card.

Whenever an Aura you control enters, untap Fuming Lawmaker.
{1}, {T}: For each opponent, Fuming Lawmaker deals 1 damage to that player or a planeswalker they control. Scry 1.

When Political Opportunist enters, you may shuffle the cards from your hand into your library, then draw that many cards.

You may cast Hunter of the Moon-Serpent from your graveyard as long as you gained life this turn.

Whenever you sacrifice a permanent, you may put a -1/-1 counter on target creature.

Beachhead Partisan has first strike as long as it's attacking.
When Beachhead Partisan enters, it deals X damage to any target, where X is the number of tapped creatures you control.

Flash
When Cocky Bladesinger enters, it gains first strike, lifelink, and haste until end of turn.

{R}{W}, {T}: Femourri Archer deals damage equal to its power to any target. You gain that much life.

When Heirloom Seeker enters, you may search your library for an Equipment card, reveal it, then shuffle and put that card on top of it.
Heirloom Seeker has first strike as long as it's equipped.

Flying, lifelink, haste
At the beginning of the end step, sacrifice Helix Entity.

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.

Whenever one or more creatures you control with counters on them attack, draw a card.

Flash
When Hexfang Ascetic enters, return target spell to its owner's hand.

When Sacrifice to Setar dies, surveil X, where X is the amount of damage dealt to them this turn. Draw a card. Then if X is 3 or greater, you may return Sacrifice to Setar to the battlefield transformed.

Mianju enters with your choice of a menace or +1/+1 counter on them.
Whenever two or more creatures in Mianju's pack attack, mill three cards, then return a creature card from your graveyard to your hand. (Two or more creatures you control with equal power are in a pack.)