msem-instigator

Flash (You may cast this spell any time you could cast an instant.)
When Majestic Hippocamp enters, target creature gets -2/-0 until end of turn.

First strike
When Majestic Monitor enters, if you control a legendary creature, creatures you control get +1/+0 and gain haste until end of turn.

{T}: Add one mana of any color.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Whenever Manipulator of Waves attacks, mill three cards. Then create a 0/0 blue Elemental Serpent creature token with “This creature gets +1/+1 for each five cards in your graveyard.”

Improve {1}{W} ({1}{W}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Prevent all combat damage that would be dealt to attacking embattled creatures you control. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Marinton Occultist can't block or be blocked.
Whenever one or more cards are put into a player's graveyard from their library, Marinton Occultist gets +1/+1 until end of turn.

Menace (This creature can't be blocked except by two or more creatures.)

Menace
When Marrow Raptor enters, you may sacrifice a land or exile a land card from your graveyard. If you do, put a +1/+1 counter on it.

Marrowskitter can't block and can't be blocked.
{3}{B}{B}: Return Marrowskitter from your graveyard to the battlefield. Create a token that's a copy of it.

Whenever you sacrifice one or more permanents, put a +1/+1 counter on Marsh Dweller.

First strike
Whenever Martial Maestro attacks, other attacking creatures you control get +1/+0 until end of turn.

Trample
Whenever you cast a spell with more colors than the number of counters on Martoob Beastkeeper, put a +1/+1 counter on Martoob Beastkeeper.

First strike

Sacrifice Masahita's Servant: Exile the top card of your library. Until end of turn, you may play that card.

At the beginning of your upkeep, exile the top card of your library. Masahita, Bloodtongue deals damage to you equal to that card's mana value. Until end of turn, you may play that card.

{T}: Add {C}.
Whenever you tap Masamori Initiate for mana, you may mill a card.

When Masha's Lightbound becomes tapped for the first time each turn, untap Masha's Lightbound and each other creature you control.
{W}, {T}: Exile target card from a graveyard.

Whenever Masha's Vanguard deals damage to a player, you may put a creature card with mana value X or less from your hand onto the battlefield, where X is the amount of damage dealt this way.

Masked Impersonator can't be blocked.
Art of war — At the beginning of your end step, if Masked Impersonator dealt damage to an opponent this turn, you may have it become a copy of target creature you control except it has this ability.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Masked Lancer has first strike as long as it's attacking.
Whenever Masked Lancer mentors a creature, that creature gains first strike until end of turn.

Flying
When Masked Stalker enters, target player discards a card.

Whenever one or more cards are put into exile from anywhere, target opponent loses 1 life.
Whenever one or more creatures you control deal combat damage to a player, you may pay 2 life. If you do, purge. (Exile two cards that share a type from graveyards. If you do, draw a card.)

Whenever another creature enters, Masquerading Bohemian becomes a copy of that creature except it's a Noble in addition to its other types and it has this ability.

Whenever you cast a spell, if it isn't your main phase, choose one. This ability triggers only once each turn.
• Put a +1/+1 counter on Master of Three Paths.
• Tap target creature.
• Master of Three Paths phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever an experience ability puts a +1/+1 counter on a creature you control, put a +1/+1 counter on that creature.