msem-instigator

Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)
Whenever Merciless Exiled deals combat damage to a player, scry 2.

Whenever one or more creatures deal combat damage to you, exile one of those creatures.
You may cast cards exiled with Merciless Mirror and may spend mana as though it were mana of any color to cast those spells.

Menace
Ferocious — Whenever Merciless Xun Huang attacks, if you control a creature with power 4 or greater, defending player sacrifices a permanent.

{2}{G/U}{G/U}, {T}: Untap each non-Lizard permanent you control.

This spell can't be countered.
Whenever Meren, Bane of the Cairns attacks, exile target creature card from your graveyard. You may cast that card for as long as it remains exiled by sacrificing a creature in addition to paying its other costs.

Skip your draw step.
At the beginning of your upkeep, shuffle your hand and graveyard into your library, then draw three cards.
You can't cast more than one spell each turn.

[+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.)

Kicker {2} (You may pay an additional {2} as you cast this spell.)
Prowess
When Merkurio's Opus enters, if it was kicked, draw two cards, then discard two cards.

[+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.

Enchant creature
When Mesmerizing Shimmer enters, untap enchanted creature. It gains haste until end of turn.
You control enchanted creature.
Mirage {2}{U}{R} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Artifact spells you cast cost {1} less to cast.
{2}, Sacrifice an artifact: Target creature gains deathtouch until end of turn.

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.

Mianju enters with your choice of a menace or +1/+1 counter on them.
Whenever two or more creatures in Mianju's pack attack, mill three cards, then return a creature card from your graveyard to your hand. (Two or more creatures you control with equal power are in a pack.)

Vigilance
When Mid-Autumn Celebrants enters, create a 2/2 white Panda Bear Monk creature token with vigilance.

Once each turn, when you activate a nonmana ability, you may create a tapped 1/1 white Spirit creature token with flying.
{4}{W}{U}: You gain 1 life and draw a card.

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.

Lifelink
When Milunda, Prairie Prince enters, each opponent loses life equal to the number of storied permanents you control and you gain that much life. (Enchantments and legendary permanents are storied.)

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.

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.

Whenever an enchantment you control enters, choose one that hasn't been chosen this turn —
• Draw a card.
• Put two +1/+1 counters on target creature you control.

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

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.”)

Whenever another nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of it, except it has base power and toughness 1/1. If that creature had power 4 or greater, create two of those tokens instead.

When Mire Sculptor enters, mill three cards.
Whenever you sacrifice a permanent, you may pay {2}. If you do, return target permanent card from your graveyard to your hand.

Whenever you cast a green or blue spell, create a 1/1 green and blue Elemental creature token.
Each Elemental you control enters with an additional +1/+1 counter on it.