msem-instigator

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.)

Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, put a +1/+1 counter on Mirrorcast Battlemage.
Remove three +1/+1 counters from Mirrorcast Battlemage: Copy target instant or sorcery spell you control. You may choose new targets for the copy. Activate only once each turn.

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.

Enchant creature
Enchanted creature has distorted. (This creature can be blocked by tapped creatures but not untapped creatures.)
{1}{W}: Tap enchanted creature.

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.

Whenever a player casts an instant or sorcery spell that targets only one target or activates an ability that targets only one target, copy that spell or ability for each other target it could target. Each copy targets a different one of those targets. (A spell or ability can't target itself.)

Prowess
Whenever you cast your first noncreature spell during each of your turns, create a 1/1 blue Reflection Wizard creature token with prowess.

Target creature gets +1/+1 and gains distorted until end of turn. (It can be blocked by tapped creatures but not untapped creatures.)
Put the bottom card of your library into your hand.

When you cast this spell, copy it for each Reflection creature you control. You may choose new targets for the copies.
Mirrorstorm deals 1 damage to any target and you gain 1 life.

Target creature gets +1/+1 and gains distorted until end of turn. (It can be blocked by tapped creatures but not untapped creatures.)
Put the bottom card of your library into your hand.

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}

Flying, ward {2}
At the beginning of your upkeep, if Mirrorwing Commander is embattled, create a token that's a copy of it. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Counter target spell.

Flash
Whenever Mischievous Capuchin or another Monk you control enters, tap target creature you don't control. If it was already tapped, it doesn't untap during its controller's next untap step.

Whenever you sacrifice a permanent, Mischievous Maolu gets +1/+1 until end of turn and you gain 1 life.

Flash (You may cast this spell any time you could cast an instant.)
Flying (This creature can't be blocked except by creatures with flying or reach.)

[+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.”

Flash
Flying
When Mischievous Sprite enters,you may tap or untap target permanent.

When Miserable Portent enters, create a 1/1 black Harpy creature token with flying.
{3}{B}, Sacrifice Miserable Portent: You draw two cards and you lose 2 life.