msem-instigator

When Abyssal Nightcaster enters, each player exiles a card from their hand.
When Abyssal Nightcaster dies, you may play cards you don't own from exile this turn.

After a player chooses two or more modes while casting a spell, you may pick one of those modes. That mode is no longer chosen. (That player doesn't pick targets or pay costs related to that mode. If a mode is chosen multiple times, only one instance of that mode is lost.)

Enchant creature
Enchanted creature gets +2/+2. Other creatures you control get +1/+1.

Flying
{2}{W}, Exile a non-Spirit creature card from your graveyard: Create a 1/1 white Spirit creature token with flying.

Non-Human creatures you control get +1/+0.

This spell costs {2} less to cast if you've cast both an instant spell and a sorcery spell this turn.
Haste

Death knell — Each opponent loses 1 life. You gain life equal to the amount of life lost this way. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)
Whenever a creature dies, trigger a death knell of a permanent you control.

Flash
Flying, first strike, lifelink

Creatures your opponents control get -1/-0.

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

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.

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.

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.”

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

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.)

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

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

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

Lifelink
Whenever an opponent loses life, you may pay {2}. If you do, choose one—
• That player discards a card.
• Put a +1/+1 counter on Adversary Ancestor.

Flying
Aedryd, Spectral Liege's power and toughness are each equal to the number of creatures you control.
{2}{W/U}: Another target creature you control gains flying until end of turn. When that creature leaves the battlefield this turn, create a 1/1 white Spirit creature token with flying.

First strike, menace
Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
At the beginning of each combat, you may pay {1}. When you do, another target creature gains melee until end of turn. (If a creature has multiple instances of melee, each triggers separately.)