msem-instigator

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

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.

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.

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.”

Other creatures you control get +2/+2.

Creatures you control with flying get +1/+1.
Whenever a creature you control with flying deals combat damage to a player, you may pay {U}. If you do, draw a card.

Create a token that's a copy of target creature you control.
Fabled {5}{U}{U} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)

Prowess
Libraries can't be searched.
Spells you cast cost {1} less to cast for each permanent you control but don't own.

Flash
When Mokuteki Ambusher enters, until end of turn, other creatures you control gain “{T}: This creature deals 1 damage to any target.”

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.)
Double strike
If this creature would deal noncombat damage, it deals double that damage instead.

Whenever you cast a noncreature spell, put a hatch counter on Molten Incubation. Then if it has five hatch counters on it, sacrifice it and choose one —
• Create a 5/5 red Dragon creature token with flying.
• Molten Incubation deals 20 damage to each creature.

Molten Mire enters tapped unless you control a basic land.
{T}: Add {B} or {R}.

Molting Abomination can't be blocked by creatures with power 2 or less.
Whenever Molting Abomination deals combat damage to a player or planeswalker, create a tapped 3/2 colorless Horror creature token. Put a stun counter on that token. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Cast this spell only during your turn.
Counter target spell.

When Monk of Mid-Autumn enters, choose one —
• Put a double strike counter on Monk of Mid-Autumn.
• Destroy target artifact or enchantment.
• Monk of Mid-Autumn deals 2 damage to target tapped creature and you gain 2 life.

{W}{U}, {T}: Target creature gets +2/+2 and gains flying until end of turn.
{U}{B}, {T}: Target player mills three cards.
{B}{R}, {T}: Monolith of Ages deals 3 damage to any target.
{R}{G}, {T}: Target creature gets +4/+2 and gains trample until end of turn.
{G}{W}, {T}: Populate. (Create a token that's a copy of a creature token you control.)

Reach
At the beginning of your end step, if you've gained 3 or more life this turn, create a 3/3 black Demon Horror creature token and each player loses 3 life.

Exile target creature. That creature's controller reveals cards from the top of their library until they reveal a creature card. That player puts that card onto the battlefield, then shuffles the rest into their library. If you own that card, it enters with an additional X +1/+1 counters on it, where X is its power.

When Monstrous Hunter enters, destroy up to one target creature.
At the beginning of each end step, if a creature died this turn, you draw a card and you lose 1 life.

Whenever a creature you control enters, put a devotion counter on Monument of the Masses.
At the beginning of your upkeep, if Monument of the Masses has thirty-five or more devotion counters on it, you win the game.

Whenever you draw your second card or cast your second spell each turn, put a +1/+1 counter on Monument to Quia.
{U}: Monument to Quia becomes a 0/0 Statue artifact creature with flying until end of turn.

Moonchaser Meadow enters tapped.
{T}: Add {W}.
{1}{W}{W}, {T}: Put a loyalty counter on each planeswalker you control.

Whenever a creature dealt damage by Mooncursed Howler this turn dies, create a 2/2 red Werewolf creature token with first strike.