msem-instigator

When Chaotic Pupil enters, harmonize twice. (To harmonize, trigger up to one harmony of a permanent you control.)
Harmony — Draw a card, then discard a card.

Artifact creatures you control can't be blocked by nonartifact creatures.
{2}{U}{R}: Put a +1/+1 counter on an artifact creature you control or a progress counter on a Project you control.

Flying, haste
Miyoga Firebird attacks each combat if able.
Whenever you cast your third instant or sorcery spell this turn, you may return Miyoga Firebird from your graveyard to the battlefield.

Rapport — Whenever Trae, Serpent's Grasp and at least one other creature you control become tapped, each player draws a card. Then Trae, Serpent's Grasp deals 2 damage to each opponent with four or more cards in hand.

Reach
When Ambush Predator enters, you may return target Horror creature card from your graveyard to your hand.
When Ambush Predator dies, exile it and create a 3/2 green Horror creature token.

Whenever Imisti, Elven Insurgent attacks, mill two cards. When you do, you may return target land card from your graveyard to your hand.
{X}{B}{G}: If Imisti has no +1/+1 counters on it, put X +1/+1 counters on Imisti. Activate only as a sorcery.

Jara Favored gets +2/+2 as long as you've lost life this turn.

When Rat King enters, create two 1/1 black Rat creature tokens with “This creature can't block.”
Whenever Rat King or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Deathtouch, menace
Slayer of the Famed must be blocked each combat if able.

Trample
{3}{B}{G}, Discard two cards: Return Tammil and Sulei, the Guides and another target creature card from your graveyard to the battlefield tapped.

When Barbarian Hoarders enters, you may attach target Equipment you control to it.

Haste
When Collapsing Star Viper enters, you may tap target permanent with mana value X or less.
At the beginning of your upkeep, return Collapsing Star Viper to its owner's hand.

Whenever a Hound you control is dealt damage, Greypelt Emissary deals 1 damage to any target.
Whenever Greypelt Emissary attacks, you choose how target creature blocks this combat.

{1}, {T}: Search your library for a card named Greypelt Trooper, reveal it, put it into your hand, then shuffle. Activate only as a sorcery.

First mate—Your starting deck contains at least twelve Vehicles. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Haste
{R}{W}, {T}: You may put a Vehicle card from your hand onto the battlefield. That Vehicle gains haste and becomes an artifact creature until end of turn.

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Honorable Mentor mentors a creature, that creature and Honorable Mentor each gain first strike until end of turn.

Whenever Lackeybot deals damage to a player, choose an artifact card with mana value X or less at random, where X is the amount of damage dealt. You may create a token that's a copy of that card.

First strike, haste
Whenever Lothaire attacks, create a 0/0 colorless Reflection creature token that's tapped and attacking. Creatures you control get +1/+1 until end of turn.
{2}{R}{W}: Put a +1/+1 counter on each creature you control.

Trial 2 (As you cast this spell, an opponent of your choice may pay 2 life. If they don't, they fail the trial.)
When Nascent Adversary enters, if the trial was failed, it gains haste and first strike until end of turn.

Other creatures you control get +1/+0.
{R}{W}: Create a 1/1 red and white Warrior creature token. That token gains haste. Exile it at the beginning of the next end step. Activate only as a sorcery.

Haste
Whenever Quinn or another creature you control enters, tap all creatures your opponents control.

Flash
First strike
If you cast Taiyohata Champion during your declare attackers step, it enters tapped and attacking.

Lands you control have hexproof.
{2}{G}{U}: Rouse 2. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

Vision (Whenever this or another creature you control enters, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Dusk Occultist envisions a creature card, draw a card.

Flying
Whenever Haerthach, the Wight King deals combat damage to a player, you may sacrifice another creature. When you do, create a 1/1 white Spirit creature token with flying. Return the sacrificed card to the battlefield tapped and under your control at the beginning of the next end step.