msem-instigator

Flying
When Ascetic of the Folded Fan enters the battlefield, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Each creature you control with a +1/+1 counter on it has vigilance.

Whenever you cast an Inscription spell, you may choose target creature you control. If you do, as that Inscription resolves, exile it inscribed onto that creature instead of putting it anywhere else.

First mate — Twelve or more cards in your starting deck are Dragons or have “Dragon” in their printed rules text. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Dragon spells you cast cost {1} less to cast.
Whenever Ashe attacks, it deals X damage to any target, where X is the number of Dragons you control.

Flying, trample
When Ashen Persecutor enters the battlefield, target opponent reveals their hand. You choose a nonland card from it. That player discards that card and you gain life equal to its mana value.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
This creature can't be sacrificed.

Haste
{T}, Sacrifice a creature: Ashspeaker deals 1 damage to any target.

Whenever Aspect of An'yama attacks, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
Spells you cast from your graveyard, activated abilities of cards in your graveyard, and reprise costs of spells you cast cost {1} less.

Flying, vigilance
Whenever a land enters the battlefield under your control, create a 2/2 green Ox creature token.
{3}{W}, Tap three untapped Oxen you control: Put a +1/+1 counter on each creature you control.

When Asphodel Gravedealer dies, choose one —
• Put a +1/+1 counter on target creature you control.
• Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Whenever a storied permanent enters the battlefield under your control, tap target creature an opponent controls. (Enchantments and legendary permanents are storied.)

Aspiring Dragon has flying and haste as long as you control another Dragon.
{2}{R}{R}: Aspiring Dragon gets +3/+0 until end of turn.

Rhapsody {3}{W}{W} (Pay {3}{W}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Lifelink

Whenever Aspiring Hero attacks alone, put a +1/+1 counter on it.
When Aspiring Hero dies, each opponent gains life equal to its power.

Vanguard — Whenever a creature you control attacks alone, it gets +1/+1 until end of turn.

First strike
Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.) [3/3]
[Lore I-II] Put a +1/+1 counter on each of up to two other target creatures you control.
[Lore III] Remove all lore counters from Astral Capricine. Create two 0/1 white Goat creature tokens.

Menace
Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.) [3/3]
[Lore I-II] Exile the top card of your library. You may play that card this turn.
[Lore III] Remove all lore counters from
Astral Cerberus. It deals 3 damage to up to one target creature.

Deathtouch
Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.) [3/3]
[Lore I-II] You may sacrifice another creature. If you do, draw a card.
[Lore III] Remove all lore counters from Astral Leech. Each opponent sacrifices a creature.

Ward—Exile three cards from your graveyard. (Whenever this permanent becomes the target of a spell or ability an opponent controls, counter it unless that player exiles three cards from their graveyard.)
Menagerie — Astralhorn Familiar gets +2/+2 as long as there are five or more creature types among creatures you control.

When Astute Prophet enters the battlefield, draw a card. If you control a legendary creature, draw two cards instead.

Whenever Atieh's Destiny or another creature enters the battlefield under your control, you gain 1 life and scry 1.

Flying
Whenever Atieh's Disciple attacks, scry 1.

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

Tribute 3 (As this creature enters the battlefield, an opponent of your choice may put three +1/+1 counters on it.)
When Atuum Serpent enters the battlefield, if tribute was paid, it gains defender. (This effect lasts indefinitely.)

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

Flying
Whenever August Sunbird attacks, create a token that's a copy of another target creature you control, except it's 1/1, and it's tapped and attacking. Sacrifice the token at the beginning of the next end step.