msem-instigator

({T}: Add {B}.)
As Midnight Gate enters, you may pay 1 life. If you don't, Midnight Gate enters tapped.
Basic lands you control have “{T}: Add {B}.”

{T}: Add {C}.
{3}: Mill two cards, then return Midnight Keep from your graveyard to the battlefield tapped.

When Mighty Totem enters, scry 1.
{1}{G}, Sacrifice Mighty Totem: Target creature gets +3/+3 until end of turn.

MiliCore Barracks enters tapped.
{T}: Add {B} or {R}.
{B}{R}, {T}: Create a Function token with “Deathtouch.” Activate only if an opponent lost life this turn. (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Mind Palace enters tapped.
{T}: Add {U} or {B}.
When Mind Palace enters, you may put a loyalty counter on a planeswalker you control.

As Mind-Mute enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.
{5}: Return Mind-Mute to its owner's hand.

Creatures with power greater than the number of cards in their controller's hand can't attack.

When Mindwave Rod enters, attach it to target creature you control.
Equipped creature gets +1/+1 and has “Whenever this creature deals combat damage to a player, draw a card.”
Equip {2}

{2}{R}, Sacrifice Minefield Bomber: It deals 2 damage to any target.
Cycling {2/R} ({2/R}, Discard this card: Draw a card.)

Flying
When Mineral Retriever enters, create a Treasure token.

Equipped creature gets +1/+1. If it's a token, it gets +3/+3 instead.
Equip {2}

At the beginning of your upkeep, choose another planeswalker you control. You may activate that planeswalker's loyalty abilities twice this turn rather than only once.
[+2]: You may put a land card from your hand onto the battlefield. If you don't, each player draws a card.
[–2]: Exile target permanent. Return it to the battlefield under its owner's control at the beginning of the next end step.
[–7]: For each land on the battlefield, add one mana of any type that land could produce.

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.)
When the fourth spell of a turn is cast, you may unlock Mirror Cipher. If the revealed card is an instant or sorcery card, cast it without paying its mana cost and copy it. You may choose new targets for the copy.

Whenever equipped creature blocks or becomes blocked by a creature, you may have equipped creature become a copy of that creature until end of turn.
Equip {1}

Mirrorgate enters tapped.
When Mirrorgate enters, you choose a nonbasic land card name other than Mirrorgate, then each player chooses a color.
Lands with the chosen name are lands with “{T}: Add one mana of any of the chosen colors,” and lose all other abilities, card types, and land types.
{T}: Add one mana of any of the chosen colors.

The “legend rule” doesn't apply to artifacts and enchantments you control.
Equipped creature gets +1/+1 for each artifact and/or enchantment you control.
Equip {2}

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.

At the beginning of your upkeep, you may choose one —
• Put a card from your hand on the bottom of your library. If you do, draw a card.
• Discard a card. If you do, put the bottom card of your library into your hand.

Modular Mercenary gets +1/+0 and has first strike as long as you control a creature with a +1/+1 counter on it.

You may play Molten Basin from your graveyard as long as seven or more cards are in your graveyard.
Molten Basin enters tapped.
{T}: Add {B} or {R}.
Cycling {1}{B}{R} ({1}{B}{R}, Discard this card: Draw a card.)

({T}: Add {B} or {R}.)
Molten Falls enters tapped.
{1}, {T}: Add {B}{B} or {R}{R}.

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

{T}: Add {G} or {U}.
{G}{U}, {T}: Return target creature you control to its owner's hand.

{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.)