msem-instigator

Flying
Whenever another creature enters the battlefield under your control, 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 the battlefield, 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.

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

Flash
When Adiran Distractor enters the battlefield, 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 the battlefield 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.”)

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Creatures can't attack you or planeswalkers you control unless their controller pays {2} for each of those creatures.

Reach
{T}: Adorned Flamebinder deals 1 damage to any target. Activate only if Adorned Flamebinder is embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Civilized — Adorned Naga gets +2/+0 and has menace as long as you control an artifact, a creature, and an enchantment.

Flying, haste
Whenever Adoroth, the Baneful attacks, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)
{1}{R}{R}: Adoroth, the Baneful deals 4 damage to any target. Activate only if you have no cards in hand.

Each spell you cast with flash or haste costs {1} less to cast.
Each creature you control with flash or haste gets +1/+0.

Noncreature spells you cast cost {1} less to cast.

Advanced Powercell enters the battlefield tapped.
{T}: Add one mana of any color.

Whenever you cast an Adventure spell, put a +1/+1 counter on Adventurer Extraordinaire.

{2}, Sacrifice Adventurer's Amulet: Search your library for a basic land or Satrapy card, reveal it, put it into your hand, then shuffle.

Flying
As long as there are five or more different creature types among creatures you control, Adventuring Guildmage gets +1/+0 and has hexproof.

As long as you control four or more differently named lands, creatures you control get +1/+1.
As long as you control a land named Far-Off Lands, creatures you control get +1/+1.