msem-instigator

Flying, menace

Rhudai Fieldtiller gets +1/+1 for each enchanted land you control.
At the beginning of your end step, untap each enchanted land you control.

Whenever one or more cards are put into an opponent's graveyard from their hand or library, Cackling Tormentor deals 2 damage to any target.

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

You may activate abilities of nonland permanents your opponents control.

Destroy target creature. Then if you control a Wizard, that creature's controller loses 1 life for each creature card in their graveyard.

{T}: Add one mana of any color in your commander's color identity.

When Ankulith Shard enters, draw a card.
{1}, {T}: Add one mana of any color.

This spell costs {1} less to cast for each foretold card you own in exile, each permanent you control with foretell, and each card with foretell in your graveyard.
Flying
When Tyrant of Prophecies enters, it deals 3 damage to any target.

{T}: Add {C}.
{T}, Exile Memorial of the Fallen: Shuffle your graveyard into your library.

Trample
Savage Mammoth gets +1/+1 for each land you control.
Ride {4}{G} ({4}{G}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Ghostly Hounds mentors a creature, that creature can't be blocked this turn.

Flying
As long as it's your turn, you and Angel of Succor have hexproof.
Untap all lands you control during each other player's untap step.

Harmony — Tap target creature. That creature doesn't untap during its controller's next untap step.
When Chilling Musician enters, harmonize. (Trigger up to one harmony of one permanent you control.)

[+1]: Search your library for a land card, put it onto the battlefield, untap it, then shuffle. Sacrifice a land.
[–2]: Destroy target noncreature permanent. Its controller may search their library for a basic land card, put that card onto the battlefield, then shuffle.
[–6]: Return any number of land cards from your graveyard to the battlefield and untap them. They become 3/3 creatures with haste in addition to their other types.

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever one or more creatures you control survive damage, add a quest counter.
1 — You may put a creature card with mana value 2 or less from your hand onto the battlefield.
2 — Put two +1/+1 counters on target creature you control.
3 — Choose target creature you control. You draw cards equal to half that creature's power, rounded down.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
This creature can't be blocked by creatures with power 1 or less.

{T}: Add {C}.
{T}: Add {U}, {R}, or {W}. You can't spend this mana to cast a monocolored spell.

Whenever one or more creatures you control attack, you may put a progress counter on Stormcannon Testing.
[PROGRESS 2-3] {T}: Target creature gets +2/+0 until end of turn.
[PROGRESS 4+] {T}: Target creature gets +2/+0 and gains double strike until end of turn.

Enchant player
At the beginning of enchanted player's end step, gain control of a permanent they control.

Creatures can't attack you unless their controller pays {2} for each of those creatures.
Mirage {1}{U} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

When Fleshwrithe Ghoul enters, each player sacrifices a creature.
Revive {4}{B} ({4}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

When Keeper of Dark Shadows enters, if it's not a token, target opponent reveals their hand. You may choose a creature card from it. Create a token that's a copy of that card, except it's a colorless Spirit.

Menace
{3}{R}: Transform Troublesome Throng. Activate only if it's attacking.

When Aureate Golem enters, create a Treasure token. Each other player creates a tapped Treasure token. (They're artifacts with “{T}, Sacrifice this artifact: Add one mana of any color.”)