msem-instigator

Flying
Whenever Atieh's Disciple attacks, scry 1.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Flash
When Atieh enters, return target noncreature spell to its owner's hand.
{W}{U}: Angel — You gain 2 life and draw a card.
{2}{W}{U}: Elder — Atieh gains “Each opponent can't cast more than one spell each turn.”

First strike (This creature deals combat damage before creatures without first strike.)
When Attended Knight enters, create a 1/1 white Soldier creature token.

Attentive Glider gets +2/+2 and has flying as long as you cast an Adventure spell or a permanent you controlled explored this turn.

Prowess
Other Monks you control get +1/+1.
Whenever you cast a spell during another player's turn, untap each Monk you control.

{1}, Sacrifice a creature or enchantment: Exile the top card of your library. You may play that card this turn.

Flying
Other creatures you control with flying get +1/+1.

When Auramancer enters, you may return target enchantment card from your graveyard to your hand.

Once each turn, when you cast a noncreature spell, create a 1/1 colorless Human creature token. Put a prowess counter on it.

When Automated Blademaster enters, create a colorless Equipment artifact token named Sword with “Equipped creature gets +1/+1” and equip {1} and attach it to Automated Blademaster.

Reach
When Automated Overwatch enters, create a Function token with “If this spell would create one or more tokens, it creates twice that many of those tokens instead.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

{T}, Tap an untapped creature you control: You draw a card and you gain 1 life.

When Autumnal Resonants enters, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Create a 3/3 red and green Elemental creature token with haste.

At the beginning of your end step, if you control two or more artifacts and/or enchantments, transform Avacyn's Partisan.

{2}: Avaricious Ghul gets +1/+1 until end of turn. If mana from a Treasure was spent to activate this ability, put a +1/+1 counter on Avaricious Ghul instead.

Deathtouch
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Avatar of Amosis enters, if tribute wasn't paid, you may destroy target creature.

Menace (This creature can't be blocked except by two or more creatures.)
Avatar of Basat can't block.

Crocodile creatures you control get +1/+1.
Avatar of Senmut and Crocodile creatures you control can't be blocked as long as you control four or more Islands.

Reach, trample
If a +1/+1 counter would be put on another creature you control, instead put a +1/+1 counter on that creature and on Avatar of the Natural.

First strike
When Avaz Cataphract enters, judge another target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)

Flying
Harmony — Until the end of your next turn, you may cast target instant or sorcery card from your graveyard. If that card would be put into your graveyard, exile it instead.
When Aven Acoustimancer enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Kicker {U} (You may pay an additional {U} as you cast this spell.)
Flying
If Aven Ranger was kicked, it enters with a +1/+1 counter on it.

Flying, vigilance

Whenever you gain life, amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control one, create a 0/0 black Zombie Army creature token first.)
If you would gain life except for the first time each turn, instead each opponent loses 1 life. (If multiple sources would cause you to gain life at the same time, choose one to be first.)

Whenever you cast an Azra spell, mill three cards.
Whenever you cast a Demon spell, you may return an Azra card with lesser mana value than that spell from your graveyard to the battlefield.