msem-instigator

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.”)

Double strike

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.

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

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 another colorless creature: Put a +1/+1 counter on target creature.

Until end of turn, target creature gets +2/+2 and gains “Whenever this creature attacks, you may post a bounty on target creature.” (Put a bounty counter on that creature. It has “When it dies, each opponent draws a card” as long as it has a bounty counter on it.)

Haste
Whenever Mukal Charger attacks during your first combat phase each turn, untap all Constructs you control. After this phase, there's an additional main phase followed by an additional combat phase.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

Haste
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

As an additional cost to cast this spell, pay {3} or discard a card.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

Trample
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)
Whenever Mukal Warleader attacks, the next Construct spell you cast this turn costs {1} less to cast.

When Mul Daya Elder enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Whenever a land you control enters, put a +1/+1 counter on Mul Daya Elder.

Exile a nonland card from your graveyard: For each colored mana symbol in that card's mana cost, add one mana of that color. Activate only once each turn. (For example, if the card's mana cost is {3}{G}{G}{W}, you add {G}{G}{W}.)

Whenever a nontoken creature you control enters, if it shares no creature types with other creatures you control, draw a card.

Multipurpose Mannequin gets +1/+1 for each permanent attached to it.

As an additional cost to cast this spell, pay {2} or put a -1/-1 counter on a creature you control.
Munitions Explosion deals 3 damage to any target.

Whenever a creature with flying attacks you, gain control of that creature at end of combat.

Enchant creature
Whenever enchanted creature attacks, it gets +3/+3 and gains trample until end of turn.

Trample
Whenever Muse of Summer Revelry enters or you cast a spell with power 4 or greater, choose one —
• You gain 3 life.
• Create a 2/2 green Wolf creature token.
• Draw a card.

Untap all creatures that attacked this turn. After this main phase, there is an additional combat phase followed by an additional main phase. For each planeswalker you control, you may activate its loyalty abilities an additional time this turn.

At the beginning of your upkeep, germinate. Then if creatures you control have total power 10 or greater, transform Mushroom Merchant. (To germinate, put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

{T}: Add {C}.
Whenever Mustering Grounds becomes tapped, if it's enchanted, you may pay {2}. If you do, create a 1/1 white Soldier creature token with vigilance.

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

First strike
When Mutilated Warrior enters, you may have it deal damage to each player equal to the number of Warriors you control.