msem-instigator

At the beginning of combat on your turn, up to one target artifact you control becomes a creature in addition to its other types and gains “This creature's power and toughness are each equal to the number of artifacts you control” and “{U}: Exile this creature, then return it to the battlefield under your control.”

When Adamant Healer enters, you may move any number of counters from target creature onto another target creature with the same controller.

Indestructible
Legendary permanents you control have indestructible.

Whenever a -1/-1 counter is put on a creature, you may create a 1/1 green Elf Druid creature token.

Lifelink
Converge — When Adapted Explorer enters, it deals X damage to up to one target tapped creature, where X is the number of colors of mana spent to cast it.

{1}: Choose one. Activate only once each turn.
• Adaptive Servitor gets +1/+1 and gains first strike until end of turn.
• Adaptive Servitor gets +2/+0 and gains trample until end of turn.

{T}, Sacrifice Adaptive Terrains: Search your library for a basic land card and put it onto the battlefield tapped, then shuffle.

{G}: Tap Adaptive Troll. It gains indestructible until end of turn.
At the beginning of each upkeep, if Adaptive Troll was dealt lethal damage last turn, put a counter of your choice on it from among vigilance, deathtouch, reach, trample, and +1/+1.

Flying
Whenever another creature you control enters, Adavene, Dean of the Arts deals 1 damage to each opponent.
Whenever a creature you control deals combat damage to a player, you may exile it, then return it to the battlefield.

When Adept Electromancer enters, scry 2, then reveal the top card of your library. If it's an instant or sorcery card, put it into your hand.

{T}: Adept Fisherman voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Adept Fisherman phases in, you gain 2 life.

Whenever Adept Lieutenant attacks, 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.”)
{1}, Sacrifice an Idol: Put a +1/+1 counter on Adept Lieutenant.

At the beginning of your upkeep, if you control four or more Swamps, you may exile target creature card from your graveyard. If you do, create a tapped token that's a copy of it except it's a black Mummy.

When Adept of Rations enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Tokens you control have “{2}, {T}, Sacrifice this token: You gain 3 life.”

Prowess
When Adept of Signals enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Tokens you control have “{2}, {T}: Sacrifice this token: Draw a card.”

Lifelink
When Adept of Transfusions enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Tokens you control have “{1}, {T}, Discard a card, Sacrifice this token: Draw a card.”

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Flash
When Adiran Distractor enters, return up to one target creature you control and up to one target creature you don't control to their owners' hands.

{T}: Add one mana of any type that a land an opponent controls could produce.

As an additional cost to cast this spell, exile two permanent cards from your graveyard.
You may cast Adiran Survivors from your graveyard.

Converge — Admin of Asthenia enters with a +1/+1 counter on it for each color of mana spent to cast it.
Admin of Asthenia can't attack unless its power is 4 or greater.

Whenever you cast a Pirate spell, create a 1/1 blue and red Pirate creature token with haste.

Haste
Whenever two or more creatures you control deal combat damage to a player, tap those creatures, then gain control of target creature you don't control until end of turn. Untap that creature. It gains haste until end of turn. After this phase, there's an additional combat phase.

As long as it's your turn, Otto is an Otter Soldier creature with indestructible and “This creature's power and toughness are each equal to twice the number of creatures you control.”
[+1]: Create a 2/2 green and white Otter Soldier creature token.
[–8]: Draw cards equal to the greatest power among creatures you control, then you gain life equal to the greatest toughness among creatures you control.

Menace
Whenever a creature an opponent controls dies, 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.”)