msem-instigator

Skip your draw step.
At the beginning of your end step, discard a card. If you do, create a 4/4 white Angel creature token with flying. If you can't, sacrifice Mark of Hubris.

Flying
Whenever you tap a land for mana, add one mana of any type that land produced.
At the beginning of each end step, if you control no untapped lands, transform Martoob, Blessing of Water.

Indestructible
Marva of Endless Inspiration can't attack or block unless you've cast a spell with mana value 4 or greater this turn.
At the beginning of your end step, return a card at random from your graveyard to your hand. If it's a land card, return it to the battlefield instead.

[+1]: Discard a card. If you do, draw a card.
[–X]: Marzen deals X damage to you. Exile the top X cards of your library. Until your next turn, you may play those cards.
[–7]: You get an emblem with “If you would draw a card, you may draw three cards instead.”

At the beginning of your upkeep, exile the top card of your library. Masahita, Bloodtongue deals damage to you equal to that card's mana value. Until end of turn, you may play that card.

Creatures your opponents control attack each turn if able.
Blocking creatures you control get +4/+0.
{W}: Untap Masha, Hero of Pelastrov.

Destroy all creatures. For each creature destroyed this way, its controller draws a card.

Flying
Whenever you cast an instant or sorcery spell from your hand, you may cast an instant or sorcery card with mana value less than or equal to that spell's mana value from your graveyard without paying its mana cost. Exile that card instead of putting it into your graveyard as it resolves.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Master of Ancient Ways mentors a creature, that creature gains double strike until end of turn.

Menace
Foresight — Whenever you draw your second card each turn, search your library for a card, put it into your hand, then shuffle.

When Master of Marble Row enters, choose one —
• Create a colorless Monument artifact token with “Creatures you control get +1/+1.”
• Create a white Cloister enchantment token with “When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.”

Flash
Reach
Whenever Mattia enters or becomes tapped, put a +1/+1 counter on target creature you control.
{2}{G}, {T}: Target creature must be blocked this turn if able. Activate only as a sorcery.

Creatures you control lose poisonous and can't have or gain poisonous.
Snakes you control deal damage to players in the form of poison counters.

Trample, hexproof
When Maw of a Thousand Worlds enters, distribute X +1/+1 counters among creatures you control, where X is the number of differently named lands you control.
When Maw of a Thousand Worlds dies, you may remove any number of counters from among permanents you control. For each counter removed this way, draw a card.

Breach (Whenever this deals combat damage to a player, you may have it become an Aura Curse until your next turn. Attach it to that player.)
Recursive — As long as Mayar, Nullcrowned is a Curse, they have all nonrecursive abilities of other Curses and creatures with breach you control.
Pay 3 life: Target enchantment creature gains haste and menace until end of turn.

Whenever a player discards a card, you may draw a card and put a loyalty counter on Mei Liva, the Broken.
[0]: Target permanent's controller sacrifices it unless they discard two cards.
[–1]: Each opponent loses X life and you gain X life, where X is the number of cards in your hand.
[–3]: Target player chooses a card in their hand, then discards the rest.

[+1]: Search each player's graveyard, hand, and library for any number of cards with the same name as target nonbasic card in a graveyard and exile them. Then each player shuffles.
[–2]: Each player draws two cards, then each opponent exiles two cards at random from their hand.
[–5]: You may cast a card exiled with Mei Liva without paying its mana cost.

[+2]: Each opponent loses 2 life. Scry 2.
[–3]: Return target creature to its owner's hand. That player discards a card.
[–6]: You get an emblem with “Whenever a player discards a card, you may cast it without paying its mana cost.”

[+1]: Draw a card unless an opponent discards a card.
[–3]: Gain control of target creature until the end of your next turn.
[–6]: Choose up to four cards in graveyards. You may play those cards without paying their mana costs.

[+1]: Exile the top two cards of your library. You may play up to one card exiled this way this turn.
[–2]: Menna Al-Mejjat deals 3 damage to target creature. If that creature would die this turn, exile it instead.
[–6]: Draw cards equal to the number of cards in exile. Menna Al-Mejjat deals that much damage to any target.

As Mercantile Accords enters, choose a number.
Whenever an opponent casts a spell with the chosen mana value, you draw a card and create a Treasure token.

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.)

[+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.)