msem-instigator

Whenever Merciless Shieldbreaker enters or attacks, target opponent puts three rust counters on a permanent they control with no rust counters on it. That permanent gains “At the beginning of your upkeep, remove a rust counter from this permanent. Then if there are no rust counters on this permanent, sacrifice it and it deals 4 damage to you.”

[+1]: Merkurio deals 2 damage to target player or planeswalker. That player or that planeswalker's controller may draw a card.
[–2]: The next instant or sorcery spell you cast this turn costs {U}{R} less to cast. This effect reduces only the amount of colored mana you pay.
[–7]: You get an emblem with “Each instant and sorcery card you own has reverberate {X}, where X is its mana value.” (When you cast a spell, copy it if you paid its reverberate cost. You may choose new targets for the copy.)

Flying, haste
{X}{R}{R}, Exile an instant or sorcery card with mana value X from your graveyard: Return Merkurio's Familiar from your graveyard to the battlefield. It gets +X/+0 until end of turn.

[+1]: The next instant or sorcery spell you cast this turn costs {1} less to cast.
[–4]: Until end of turn, whenever you cast an instant or sorcery spell, Merkurio deals 2 damage to any target.
[–8]: Exile the top seven cards of your library. You may cast any number of instant and sorcery cards from among them without paying their mana costs.

Mettalia is all colors.
Mettalia has protection from each color among cards she's salvaged in exile.
When Mettalia enters, for each color, you may salvage a nonlegendary card of that color. (Exile one from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

Whenever a land you control enters, crystallize.
{10}: Shuffle any number of other permanents you control into their owner's library. Mill that many cards. Put all permanent cards milled this way onto the battlefield. Activate only during your turn and only once each turn.

Vigilance
Whenever Mikkino becomes blocked by a creature with power 3 or greater, exile that creature.

At the beginning of your end step, you may mill two cards. If you do, you gain 2 life.
[+1]: You may discard a card. If you do, draw a card.
[–2]: Exile up to six cards from your graveyard. Create a 1/1 red and green Spirit creature token for each two cards exiled this way.
[–6]: You may cast a card from your hand or graveyard without paying its mana cost. If it has {X} in its mana cost, X is 6.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
You may cast the first spell that's an enchantment, instant, or sorcery with mana value 1 you cast each turn without paying its mana cost.

Discard your hand, then draw three cards.
Mindstorm's Eye deals 3 damage to any target.

Exile target creature. (Then exile this card. You may cast the creature later from exile.)

Starting with you, each player may put a permanent card from their hand onto the battlefield. Then each player may choose a noncreature, nonland permanent. Destroy those permanents.

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.

Flying
When Mirin, Held by the Heavens dies, if your life total is less than 10, it becomes 10.

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.

Flying
Whenever you cast an instant or sorcery spell, put a +1/+1 counter on Mirrorfuse Angel, then copy that spell for each +1/+1 counter on Mirrorfuse Angel. You may choose new targets for the copies.

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.

[+1]: Scry 3.
[–2]: Choose a card name, then mill a card. If that card has the chosen name, you draw three cards. Otherwise, you draw a card.
[–6]: You get an emblem with “Play with the top card of your library revealed” and “You may play the top card of your library.”

Players play with the top card of their libraries revealed.
[+2]: Target player mills a card. Draw a card.
[+1]: Create a 1/1 blue Illusion creature token with “This gets +1/+1 for each other Illusion you control.”
[–4]: Return target creature card from a graveyard to the battlefield under your control. It's an Illusion in addition to its other types.

Flying, haste
Miyoga Firebird attacks each combat if able.
Whenever you cast your third instant or sorcery spell this turn, you may return Miyoga Firebird from your graveyard to the battlefield.

Ward—Pay 2 life.
Whenever another creature dies, put a hysteria counter on Mob of the End.
At the beginning of your first main phase, remove all hysteria counters from Mob of the End and add that much {R}.

Indestructible
As long as your devotion to black and red is less than seven, Mogis isn't a creature.
At the beginning of your upkeep, each player discards a card. Then you draw a card. If an opponent can't discard a card or discarded a land card, you create a 2/3 red Minotaur creature token.

Look at the top two cards of your library. You may put both of those cards into your graveyard or back on top of your library in any order.
Draw a card.

Align X (Choose modes with total ★ less than or equal to X. You may choose modes multiple times.)
• ★ — Whenever a creature attacks this turn, it gets +1/+1 until end of turn.
• ★★ — Create a 3/3 green Wurm creature token. It gains haste until end of turn.
• ★★★★★ — For each creature you control, create a token that's a copy of it. They gain haste.

{T}: Add {C}.
{4}: Put a +1/+1 counter on Monument of Queens. You may have it become a 0/0 Avatar creature with flying, first strike, vigilance, trample, and lifelink until end of turn. It's still a land.