msem-instigator

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.

Enchant player
Enchanted player's maximum hand size is reduced by two.

Target player reveals their hand. You choose three cards from it and exile them. Then that player exiles the top three cards of their library.

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

Each opponent discards all the cards in their hand, then draws that many cards. You discard your hand, then draw cards equal to the number of cards your opponents drew this turn.

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.

Counter target spell. Search its controller's library for a card with mana value X or less and cast it without paying its mana cost. Then that player shuffles.

Exile target spell. Then that card's owner may return it to their hand. If they do, draw a card.

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

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}

At the beginning of your end step, create a Gold token for each creature you controlled that became tapped this turn. (It's an artifact with “Sacrifice this artifact: Add one mana of any color.”)

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

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)
Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

Equipped creature gets +2/+2 and has ward {2}.
Whenever a creature you control enters, if you cast it from exile, you may attach Minstrel's Armor to it.
Equip {2}

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.

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.

Reverberate {3}{U} (When you cast this spell, copy it if you paid its reverberate cost. You may choose new targets for the copy.)
Create a token that's a copy of target creature you control.

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

When Mirror Paradigm enters, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)
Once each turn, when a sorcery card is put into your graveyard from anywhere, you may copy it. If you do, you may cast the copy. (You still pay its costs.)

The next time you cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.
Acquiesce (If you cast this spell from your hand, exile it as it resolves. When one or more creatures you control deal combat damage to an opponent, you may cast this card from exile without paying its mana cost.)

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}

Prevent all combat damage that would be dealt to creatures this turn. Creatures that attacked you this turn don't untap during their controller's next untap step.