msem-instigator

Assault {2}{R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Monstrous Hila assaults, it deals 3 damage to any target.

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.

Reach
At the beginning of your end step, if you created one or more creature tokens this turn, create a 1/2 green Spider creature token with reach.

Monumental Siege deals 5 damage divided as you choose among any number of targets. Whenever a creature dealt damage this way this turn 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.”)

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

First strike
Other Harpies you control get +1/+1 and have first strike.
Whenever a Harpy you control dies, put a +1/+1 counter on Moonlight Stalker.

Flying
When Moonlit Charmer enters, tap target artifact or creature. It doesn't untap during its controller's next untap step.

Flash
Whenever Moonlit Hunter enters or you cast a noncreature spell, tap target permanent and untap a second target permanent.

When Moonshadow Remnant enters, destroy target tapped creature.
Mirage {3}{W}{W} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

At the beginning of your end step, for each permanent with exactly one counter on it, you may choose one —
• Remove all counters from that permanent.
• Choose a kind of counter on that permanent. Put another counter of that kind on that permanent.

Return up to two target creature cards from your graveyard to your hand.

Flying
Whenever another creature you control attacks, you may pay {1}. If you do, put a +1/+1 counter on it.

Choose target creature. Scry 3, then reveal the top card of your library. You gain X life and put X +1/+1 counters on that creature, where X is the revealed card's mana value.

Target opponent mills five cards, then you exile up to two instant and/or sorcery cards from that player's graveyard. You may cast those cards for as long as they remain exiled, and you may spend mana as though it were mana of any type to cast them.

Flying
{1}{W/U}{W/U}: Creatures you control gain flying until end of turn if another creature you control has flying. The same is true for first strike, double strike, deathtouch, haste, indestructible, lifelink, menace, reach, trample, and vigilance.

Vigilance, reach, trample

Deathtouch
Other creatures you control get -1/-1.
Whenever Mother Night attacks, put target creature card from a graveyard onto the battlefield under your control.

Codex — Leyran Alpha; Fungal Whomper; Plated Crusher; Towering Hydraffe; The Terror of Shady Cove. (As this enters, conjure its contents into a shuffled face-up additional library.)
When Mother of Monsters enters, you gain 6 life.
When Mother of Monsters dies, draw a card.

Creatures you control get +2/+2 and gain first strike until end of turn.

First strike, haste
When Mounted Marksman enters, it deals 2 damage to target creature you don't control.

Haste
Whenever Mukal Charger attacks during your first combat phase each turn, untap all Constructs you control. After this phase, there's an additional main phase followed by an additional combat phase.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

When Mukal Swarmhorde enters, put a +1/+1 counter on each other Construct you control.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

[+1]: Up to one target creature gets +2/+0 until end of turn. Each player loses 1 life.
[–X]: Return target creature card with mana value X from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield.
[–7]: For each 1 life target player has less than their starting life total, create a 1/1 black Bird creature token with flying and deathtouch.

When Mul Daya Elder enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Whenever a land you control enters, put a +1/+1 counter on Mul Daya Elder.

Look at the top three cards of your library, then put them into your graveyard or back on top of your library in any order.
Draw two cards.