msem-instigator

Moonshard Crater enters tapped.
{T}: Add {R}.
{2}{R}, {T}: Each player sacrifices a nonbasic land.

{T}: Add {W}.
{W}, {T}: Target creature gains vigilance until end of turn.

(Spend a different color of mana on each {VP}.)
Moresso, Infuser of Light is all colors.
Hexproof from monocolored
Whenever you cast a spell with four or more mana symbols in its mana cost, add four mana of different colors. This ability triggers only once each turn.

{T}: Add {C}.
{1}, {T}, Sacrifice Morphic Verge: Choose two different basic land types. Create a colorless land token that's the chosen types.

Mortal Realms enters tapped unless you control two or more other lands.
{T}: Add {R}.
{T}, Pay 1 life: Add {B} or {G}.

Mosecf, the Sunseeker's Path enters tapped.
Whenever a creature you control attacks, put a creation counter on Mosecf.
{T}, Remove ten creation counters from Mosecf and sacrifice it: Creatures you control get +2/+2 and gain vigilance until end of turn. Activate only as a sorcery.

({T}: Add {B} or {G}.)
Mossy Shrine enters tapped unless you control two or more basic lands.

Sacrifice another colorless creature: Put a +1/+1 counter on target creature.

({T}: Add {U} or {B}.)
Muggy Mire enters tapped unless you control two or more basic lands.

Multipurpose Mannequin gets +1/+1 for each permanent attached to it.

Whenever a creature with flying attacks you, gain control of that creature at end of combat.

Murky Path enters tapped unless you control one or fewer other lands.
{T}: Add {U} or {B}.
Cycling {2} ({2}, Discard this card: Draw a card.)

{T}, Pay 1 life: Add {B}.
{T}, Pay 1 life, Sacrifice Murky Peat: Search your library for a Swamp card, put it onto the battlefield tapped, then shuffle.

({T}: Add {U} or {B}.)
Whenever Murmuring Falls becomes tapped, you lose 1 life unless you control two or more basic lands.

({T}: Add {G} or {U}.)
As Mushroom Lagoon enters, you may pay {1}. If you don't, Mushroom Lagoon enters tapped.

Put a +1/+1 counter on up to one target creature. (Then exile this card. You may play the land later from exile.)

{T}: Add {C}.
Whenever Mustering Grounds becomes tapped, if it's enchanted, you may pay {2}. If you do, create a 1/1 white Soldier creature token with vigilance.

You may have Mutalithic Golem enter as a copy of any land on the battlefield, except it's an artifact in addition to its other types.

Equipped creature gets +2/+2.
Concord — Whenever equipped creature attacks, if there are four or more card types among permanents you control, create a 3/3 red Shark enchantment creature token that's tapped and attacking. Exile that token at the beginning of the next end step.
Equip {1}

As Mysterious Cataract enters, you may pay 2 life. If you don't, Mysterious Cataract enters tapped.
{T}, Sacrifice Mysterious Cataract: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

{X}, Exile Mysterious Coffer: Return all nonland permanents with mana value X or less to their owner's hands.

Equipped creature gets +1/+1.
Equip {1}

{T}: Add {C}.
{3}, {T}, Sacrifice Mystical Tomb: Return target artifact, enchantment, or legendary card from your graveyard to your hand.

Naxila, the Blessed City enters tapped.
When Naxila, the Blessed City enters, you gain 2 life and draw two cards.
{T}: Add {C}{C}.