msem-instigator

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.)

When Div of Bonded Souls enters, create a 1/1 colorless Illusion creature token with “This creature is every creature type.”
Whenever a creature you control attacks, it gets +1/+0 until end of turn for each other attacking creature that shares a creature type with it.

First strike
Other Rogues you control get +1/+0 and have first strike.
{2}, Sacrifice a permanent: Return target Rogue card from your graveyard to your hand.

Flying
When Gilded Guardian dies, you may search your library for a legendary card, reveal it, put it into your hand, then shuffle.

Flying
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Ravenous Hollow enters tapped.
{T}: Add {B} or {R}.
{2}{B}{R}: Until end of turn, Ravenous Hollow becomes a Wolf creature with first strike in addition to its other types.
Scavenge {2}{B}{R}

{2/W}{2/W}: Shrapnel Golem deals 3 damage to target creature blocking it.

Spiny Ridge enters tapped. When it does, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this, then you may put that card into your graveyard.)
{T}: Add {R}.
{4}{R}: Spiny Ridge becomes a Lizard creature. (This effect lasts indefinitely.)

Flying
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Vigilance
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

Rapport — Whenever Ainok Brushwacker and at least one other creature you control become tapped, Ainok Brushwacker gains first strike until end of turn.

Motivate 2 (When this creature enters, you may motivate target creature with less power than this by putting two +1/+1 counters on it.)
{1}{W}: Target creature with a +1/+1 counter on it gains lifelink until end of turn.

Prevent all combat damage that would be dealt to Armored Axewarden as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)