msem-instigator

When Ayala's Blessing enters, put a +1/+1 counter on up to two target creatures.
Whenever an embattled creature you control dies, you may return it to its owner's hand. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

The first instant or sorcery spell you cast each turn has convoke. (Each creature you tap while casting that spell pays for {1} or one mana of that creature's color.)

Azun's Play deals damage to any target equal to the number of cards in your hand.
Quickdraw {R}{R} (When a creature you control blocks or becomes blocked, you may cast this spell for {R}{R}.)

When Azure Archaeologist enters, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
{2}, {T}, Sacrifice a Clue: Draw two cards, then discard a card.

Flying, trample
Prismatic — Whenever you cast a multicolored spell, put a +1/+1 counter on Azure Caterwauler.

Draw X cards, where X is the number of differently named lands you control.

Whenever Babbling Experiment or another creature you control enters, target player mills two cards.

When Babyscale Bruiser enters, you may reveal a creature card from your hand. If you do, Babyscale Bruiser deals damage to target creature an opponent controls equal to the revealed card's power. That creature deals damage equal to its power to Babyscale Bruiser.

First strike
Back-Alley Gnoll has lifelink as long as it's enchanted by a black Aura.
Back-Alley Gnoll gets +2/+0 as long as it's enchanted by a red Aura.

Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Back-Alley Vandal desecrates a permanent, put a +1/+1 counter on Back-Alley Vandal.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Whenever Backalley Silencer deals combat damage to a player, destroy target marked creature.

Deathtouch
When Backstage Comic enters, target player discards a card.

Lifelink
At the beginning of your end step, if you gained life this turn, put a +1/+1 counter on Backstage Manager.

When Backstage Tinkers enters, you may return an artifact card from your graveyard to your hand.

At the beginning of your end step, create a 1/1 white Soldier creature token.

Menace, haste

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Flying
{1}{W}: Demigod — Return up to one target creature card with mana value 2 or less from your graveyard to the battlefield.
{3}{W}: God — Put a +1/+1 counter on each creature you control with the least power among creatures you control.

Menace
As long as Balefire Harbinger is attacking, creatures in its pack can't be blocked unless defending player pays {1} and 1 life for each creature they control that's blocking one of those creatures. (Two or more creatures you control with equal power are in a pack.)

Flying, deathtouch

This spell costs {U} less to cast if you dealt combat damage to a player this turn with a Rogue.
Flying
When Balloon Voyager enters, draw a card.

At the beginning of combat on your turn, if there are five or more creature types among creatures you control, creatures you control get +2/+0 and gain menace until end of turn.

Whenever equipped creature attacks, it gains deathtouch until end of turn.
Sacrifice Bandit's Dagger: Target player dealt damage by equipped creature this turn reveals their hand. You choose a nonland card from it. That player discards that card.
Equip {2}

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
When Bane of Sanity enters, if it engorged a creature card, target player discards two cards.

Haste
Whenever Banished Companion attacks, it deals 2 damage to you.

Exile up to three target cards from graveyards. (Then exile this card. You may cast the creature later from exile.)