msem-instigator

Codex — Leyran Alpha; Fungal Whomper; Plated Crusher; Towering Hydraffe; The Terror of Shady Cove. (As this enters, conjure its contents into a shuffled face-up additional library.)
When Mother of Monsters enters, you gain 6 life.
When Mother of Monsters dies, draw a card.

Flying
When Mother of Owls dies, you may return target creature an opponent controls to its owner's hand.

Whenever a creature dies, put a +1/+1 counter on Mother's Disciples.

Motley Crew has no name while it's being cast. (It will always make first contact.)
{2}{R}: Creatures you control named Motley Crew get +1/+0 until end of turn.

{4}{G}: Monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)
When Mountain Bighorn becomes monstrous, you may have it fight target creature you don't control.

Kicker {2}{R} (You may pay an additional {2}{R} as you cast this spell.)
Haste (This creature can attack and {T} as soon as it comes under your control.)
If Mountain Victor was kicked, it enters with two +1/+1 counters on it.

When Mountain-Western Inventor enters, you may return target artifact card from your graveyard to your hand.
{1}, Sacrifice an artifact: Target creature can't block or be blocked this turn.

Creatures you control get +2/+2 and gain first strike until end of turn.

First strike, haste
When Mounted Marksman enters, it deals 2 damage to target creature you don't control.

Return target nonland permanent card with mana value 2 or less from your graveyard to the battlefield.
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.)

Vanishing 3 (This permanent enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever a creature dies or a time counter is removed from Mourn the Lost, you may tap target creature.

When Mourners of Mervin enters, you may sacrifice a creature or enchantment. If you do, creatures you control get +1/+1 and gain vigilance until end of turn.

Whenever another nontoken creature you control enters, you may exile a number of cards from your graveyard equal to its mana value. If you do, create a token that's a copy of it, except the token isn't legendary if the creature is legendary.
{1}{B/G}: Look at the top card of your library. You may put that card into your graveyard.

Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Players can't get counters.
Counters can't be put on permanents.

When Mouthpiece of Yhzag enters, you may have target opponent create a tapped 1/1 colorless Human creature token.
Whenever Mouthpiece of Yhzag attacks, gain control of target Human creature you don't control with mana value 3 or less until end of turn. Tap it. It's attacking.

Target creature can't be blocked this turn.

Scry 2, then reveal the top or bottom card of your library. Creatures you control get +X/+X until end of turn, where X is that card's mana value.
Draw a card.

Flash
Enchant creature
When Moved by Instinct enters, put a +1/+1 counter on enchanted creature.
Enchanted creature has haste and trample.

[+1]: Mpumo, Who Stands Alone deals 1 damage to any target and you gain 1 life.
[–X]: Exile target creature with mana value X.
[–6]: Choose up to four permanents an opponent controls. That player chooses one, then sacrifices the rest.

Whenever you tap a land for mana, add one mana of any type that land produced.
Whenever you cast a spell with mana value greater than the number of lands you control, sacrifice a land.

Sacrifice a creature or discard a card: Exile the top card of target player's library. You may cast that card for as long as it remains exiled. Any player may activate this ability but only once each turn and only during their turn.
You and permanents you control have hexproof from spells that were exiled with Mr. Jackston or that share a name with a card exiled with Mr. Jackston.

Deception {U}{B} ({U}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Ms. Moxie deals combat damage to a player, you may exile target nonland card with mana value 2 or less from your graveyard. If you do, cast a copy of that card without paying its mana cost.

Menace
Whenever Msuji Operative deals combat damage to a player, reveal the top card of your library, put it into your hand, then you lose life equal to its mana value unless you discard a card.