msem-instigator

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.

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.

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.

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.

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.

Protection from spells
When Msuji Sureshot enters, search your library for an instant, sorcery, or Aura card that targets, reveal it, put it into your hand, then shuffle.

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

Trample, haste
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)
At the beginning of your end step, sacrifice a creature.

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

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

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.

{T}: Add one mana of any color. If that mana is spent on a legendary creature spell, it enters with an additional +1/+1 counter on it.

Reverberate {2}{G} (When you cast this spell, copy it if you paid its reverberate cost. The copy becomes a permanent when it resolves.)
Mystical Echo gets +1/+1 for each other Reflection you control.
Whenever you discard a card, Reflections you control gain trample until end of turn.

{T}: Mystical Elk becomes a copy of target creature card in your graveyard. Activate only as a sorcery. (It loses this ability.)

When Naga Cultivator enters, you may put a land card from your hand onto the battlefield.

When Naiad of the Glen enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Naiad of the Glen has trample as long as it has a +1/+1 counter on it.

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
At the beginning of each end step, scry X, you gain X life, and Nakia, Infinity Seer deals X damage to up to one target creature or planeswalker, where X is the number of noncreature spells you've cast this turn.

{2}{U}, Sacrifice Nameless Drifter: Draw a card for each creature that left the battlefield this turn.

Nameless Throng can't block.
{1}{B}, Exile an artifact or enchantment card from your graveyard: Return Nameless Throng from your graveyard to the battlefield.

Trial 2 (As you cast this spell, an opponent of your choice may pay 2 life. If they don't, they fail the trial.)
When Nascent Adversary enters, if the trial was failed, it gains haste and first strike until end of turn.

Vigilance, deathtouch
Prevent all damage that would be dealt to Nataila, Raven's Repented while it's attacking or blocking alone.

Vigilance (Attacking doesn't cause this creature to tap.)