msem-instigator

Create a 1/1 blue Illusion creature token with “This gets +1/+1 for each other Illusion you control.”
Coalesce {6}{B} (You may cast this from your graveyard for {6}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Misery Keeps Company is an Illusion in addition to its other types while it's a creature.

Create a 1/1 blue Illusion creature token with “This gets +1/+1 for each other Illusion you control.”
Acquiesce (If you cast this spell from your hand, exile it as it resolves. When one or more creatures you control deal combat damage to an opponent, you may cast this card from exile without paying its mana cost.)

Put target creature into its owner's library third from the top.

Cast this spell only during the declare blockers step.
After this step there's an additional declare attackers step followed by an additional declare blockers step. (A creature can't attack or block again if it's already attacking or blocking.)
Draw a card.

Sacrifice Misleading Wisp:
Counter target spell unless its controller pays {1}.

Menace
At the beginning of your upkeep, if an opponent has more cards in hand than you, you draw a card and you lose 1 life.

Counter target noncreature spell with an odd mana value. (Zero is even.)

[+2]: Target player exiles a card from their hand at random. Until the end of that player's next turn, they may play that card.
[0]: Gain control of target creature or planeswalker until end of turn. Tap it.
[–9]: Take an extra turn after this one. During that turn, you control all opponents.

[+2]: Create a Vial token. (It's an artifact with “1, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
[–3]: Sacrifice another nonland permanent. If you do, destroy target nonland permanent.
[–9]: You get an emblem with “At the beginning of your end step, create Fallen One, a legendary 6/6 black Faerie Angel Avatar creature token with flying.”

Other creatures you control get +2/+0 and have menace.
Whenever another creature you control dies, if it wasn't sacrificed, sacrifice a creature.

Glitch {2} (Remove one [restriction] for each time you pay the glitch cost.)
Create a 3/2 red creature token named Error with trample and haste. [Exile it at the beginning of the next end step.]

Foretell {3}{U}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
Draw a card. If this spell was foretold, draw three cards instead.

Flash (You may cast this spell any time you could cast an instant.)
When Mist Lurker enters, tap all creatures you don't control.

Hexproof
Mist-Valley Ancient enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

{1}{R}, Discard a card: Draw a card. Mist-Valley Minotaurs gets +2/+0 until end of turn.

Vigilance
Ignore all effects that would prevent Mistbreaker from attacking or blocking. (If an effect says it “can't” attack or block, it still can. This ability doesn't let it attack or block if it's tapped or attack if it has summoning sickness.)

Enchant creature
Enchanted creature has hexproof.
{U}: Return Mistcharm to its owner's hand.

Poisonous 1 (Whenever this creature deals combat damage to a player, that player gets a poison counter. A player with ten or more poison counters loses the game.)
At the beginning of your upkeep, if an opponent is poisoned, you draw a card, you lose 1 life, and you get a poison counter.

Mistwake Hydra enters with X +1/+1 counters on it.
Creatures with power less than Mistwake Hydra's power can't block it.

Misty Churchyard enters tapped.
{T}: Add {W}.
{1}{W}{W}: Until end of turn, Misty Churchyard becomes a 1/4 Cleric creature with “Whenever this creature is dealt damage, put that many +1/+1 counters on it.” Activate only if you're horrific.

Dragon spells you cast cost {1} less to cast.
{1}{R}: Until end of turn, Miyoga Dragonsoul becomes a 2/2 red Dragon creature with flying and “{R}: Miyoga Dragonsoul gets +1/+0 until end of turn.” Activate only as a sorcery.

Flying, haste
Miyoga Firebird attacks each combat if able.
Whenever you cast your third instant or sorcery spell this turn, you may return Miyoga Firebird from your graveyard to the battlefield.

Flying, haste
Miyoga Flameweaver can't block.
Whenever Miyoga Flameweaver attacks, exile the top card of your library. You may play that card until end of turn.

Haste
{1}: Exile Mizujutsu Master. Return it to the battlefield under its owner's control at the beginning of the next end step.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Flying
{2}{U}{U}: Wizard — Draw a card, then discard a card. Mizuki gains “Noncreature spells you cast cost {1} less.”
{6}{U}{U}: Avatar — Draw two cards. Mizuki gains “Whenever Mizuki attacks, you may cast a noncreature spell from your hand without paying its mana cost.”