msem-instigator

Return target creature card with mana value 3 or less from your graveyard to the battlefield.
Fabled {4}{W}{W} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)

Whenever Mortified Medium or another creature enters, you gain 1 life.
As long as you have at least 10 life more than your starting life total, Mortified Medium gets +4/+4 and has flying.

Flying
{1}{W/U}{W/U}: Creatures you control gain flying until end of turn if another creature you control has flying. The same is true for first strike, double strike, deathtouch, haste, indestructible, lifelink, menace, reach, trample, and vigilance.

Flying
Whenever another creature you control enters, you gain 1 life.

(Transform this if it's not attached to a creature. Pay {1}{W} as a sorcery to unattach it.)
Enchant creature you control
Mount of Heroes's rider gets +2/+1.
Sacrifice Mount of Heroes: Counter target spell that targets you or Mount of Heroes's rider.

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

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.

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

Create two 1/1 white Soldier creature tokens. Prevent all damage that would be dealt to them this turn.

Return a permanent you control to its owner's hand.
Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Choose one —
• Return target artifact or enchantment card from your graveyard to your hand.
• Return target creature card with mana value 2 or less from your graveyard to your hand.
Cycling {2} ({2}, Discard this card: Draw a card.)

(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.