msem-instigator

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

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.

Choose up to one target land card and up to one target creature card with mana value 3 or less from your graveyard. Return one to the battlefield and the rest to your hand.

Choose one —
• Destroy target artifact or enchantment.
• Search your library for up to two basic land cards, reveal them, put them into your hand, then shuffle.

Exile target creature or planeswalker, then exile its controller's graveyard.

Target creature gets -2/-2 until end of turn. Mill two cards.

Exile target creature. If its power is 3 or greater, return that card to the battlefield under its owner's control at the beginning of the next end step.

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

Mortal Tapestry gets +1/+1 for each land card in your graveyard.
Revive {4}{G} ({4}{G}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Gain control of target creature until end of turn.
Coalesce {6}{U}{B} (You may cast this from your graveyard for {6}{U}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
As long as Mortal Whims Falter is on the battlefield, you can't lose control of permanents.

When target creature you control dies this turn, create a token that's a copy of it, except it has no mana cost.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{3}: Unlock Mortal's Conundrum. If the revealed card is black, put it into your hand. Otherwise, put it on top of your library.
At the beginning of your upkeep, if Mortal's Conundrum is unlocked, you lose 2 life.

Players can't gain life.
At the beginning of each player's upkeep, if that player has 10 or less life, they lose 1 life.

Whenever Mortified Medium or another creature enters, you gain 1 life.
As long as you have at least 10 life more than your starting life total, Mortified Medium gets +4/+4 and has flying.

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.

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.

When Moss Dweller enters, put a +1/+1 counter on another target creature.

Deathtouch

Mossvine Lurker has trample as long as it has a +1/+1 counter on it.

Vigilance, reach, trample

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

When Moth-Heart Husk dies, create a 1/1 black Spirit creature token with flying.
Revive {3}{B} ({3}{B}, Exile this card from your graveyard: Create a token that's a copy of this card, except it has no mana cost. Activate this ability only any time you could cast a sorcery.)

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.

Flying
Whenever another creature you control enters, you gain 1 life.

Whenever you sacrifice a permanent, you may put a -1/-1 counter on target creature.