msem-instigator

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)

First strike
Whenever a creature dealt damage by Mournful Newborn this turn dies, transform Mournful Newborn.

({T}: Add {U} or {B}.)
Muggy Mire enters tapped unless you control two or more basic lands.

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

Return target creature you control to its owner's hand. You gain life equal to its power.

{G}, Exile a creature card from your graveyard: Put two +1/+1 counters on target creature.

Flying
When Nest Matriarch enters, put a +1/+1 counter on another target creature you control. That creature gains lifelink until end of turn.

Target player loses X life and you gain X life, where X is the number of permanents you control with counters on them.

Create a token that's a copy of target creature card in your graveyard, except it has no mana cost.

{1}, Discard a card: Create a Gold token. (It's an artifact with “Sacrifice this artifact: Add one mana of any color.”)
{T}, Sacrifice an artifact: Draw a card.

Flying
At the beginning of your upkeep, mill seven cards, then you may cast an instant or sorcery card from your graveyard. If that spell would be put into your graveyard, exile it instead.
If you would draw a card while your library has no cards in it, you win the game instead.

Nightwatch Rallier enters with X +1/+1 counters on it.
Other artifact creatures you control get +1/+1 for each +1/+1 counter on Nightwatch Rallier.

Flying
Whenever another creature enters, you gain 1 life.

When Nomadic Patriarch enters, nourish 1. (To nourish 1, either put a +1/+1 counter on this creature or create a 1/1 white Citizen creature token.)
Remove a +1/+1 counter from Nomadic Patriarch: Put a +1/+1 counter on each other creature token you control.

Flash
When Nurse Trainee enters, you may prevent the next 2 damage that would be dealt to another target creature this turn.

{2}, {T}, Sacrifice Old Map: Search your library for a basic land card, put it onto the battlefield, then shuffle.

Target creature gets -2/-2 until end of turn.
{3}{B}{B}, Exile Ominous Wind from your graveyard: Each creature gets -2/-2 until end of turn. Activate only as a sorcery.

Vanguard — Whenever a creature you control attacks alone, put a +1/+1 counter on it.

Spells your opponents cast that target Onigori, Ema's Shield cost {2} more to cast.
Whenever Onigori deals combat damage to a player, that player can't untap more than two permanents during their next untap step.

When Oracle of Edicts enters, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Whenever an Aura you control enters, scry 1.

Harness (You may tap a creature you control as you cast this spell. If you do, reduce this spell's mana cost by that creature's power.)
Overheat deals X damage to any target.

Each instant and sorcery card you own that isn't on the battlefield has inscribe. The inscribe cost is equal to its mana cost. (Exile that spell card inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

When Paleontologist enters, search your library for up to two artifact and/or Skeleton cards and put them into your graveyard, then shuffle.

Reach
Whenever Palm Walker or another creature you control enters, you gain 2 life.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever a +1/+1 counter is put on a creature you control, tap target creature you don't control.