msem-instigator

(As you complete a condition, decode it. After all are decoded, you solve the mystery and transform it.)
When Mystery of the Dying Herds enters, create a 0/2 white Ox creature token.
A creature you control dies.
You have 4 or more life than your starting life total.

When Mythos Scribe enters, you may return target storied card from your graveyard to your hand. (Enchantments and legendary permanents are storied.)

[+1]: Create a 1/1 colorless Human creature token.
[0]: Return target permanent card with mana value 3 or less from your graveyard to your hand. If you have an insight counter, return that permanent card to the battlefield instead.
[0]: You get an insight counter.
[–1]: Target creature can't attack or block until your next turn.

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

Exile target permanent you control, then return that card to the battlefield under your control.

Look at the top seven cards of your library. You may reveal an Avatar card and/or an enchantment card from among them and put those cards onto the battlefield. Put the rest on the bottom of your library in any order.

Whenever Neo-Soul Attendant or another enchantment you control enters, you gain 1 life.

Whenever you gain life, put a +1/+1 counter on Neo-Soul Envoy.

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

Whenever New Alores Charmer attacks, you may tap target creature.

Harmony — You gain 2 life.
When New Alores Fiddler enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Choose one —
• Exile target permanent you control, then return that card to the battlefield under its owner's control.
• Return target permanent you control to its owner's hand. Draw a card.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] You gain 1 life.
[Lore III] Target creature you control gains first strike until end of turn.

Flash
{1}{W}: Return Nimble Explorer to its owner's hand.

Flying
Sacrifice Nimbus Glider: Creatures you control gain flying until end of turn.

At the beginning of combat on your turn, you may attach target Equipment you control to Nina, Master of Arms.
Whenever Nina attacks, the next artifact spell you cast this turn costs {R/W}{R/W} less to cast. (This can reduce the amount of generic mana you pay.)

Flash
When Nixie's Edict enters, tap up to two target creatures.
{2}{W}, Sacrifice Nixie's Edict: Put up to one target creature into its owner's library second from the top. Activate only as a sorcery.

Put a +1/+1 counter on target creature and a +1/+1 counter on up to one target Citizen or Peasant.

Other creatures you control get +1/+1.
As long as Nobility is in your graveyard and you control a white enchantment, creatures you control get +1/+1.

Enchant creature
Enchanted creature gets +3/+3.
Whenever enchanted creature attacks, you may put a creature card with mana value 2 or less from your hand or graveyard onto the battlefield tapped and attacking.

Exile target creature. Each player gains life equal to that creature's toughness.
Metamorph {W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

When Noble Pridelord enters, creatures you control get +1/+1 until end of turn.

Flying
Whenever another creature enters, you gain 1 life.

This spell costs {X} less to cast, where X is half the number of creatures on the battlefield, rounded down.
Destroy all creatures.