msem-instigator

[+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.

[+1]: Untap target land.
[–1]: Exile the top card of your library. You may play that card until end of turn. If a land card is exiled this way, you gain 2 life.
[–7]: Untap each land you control. Lands you control become 3/3 Elemental creatures with haste until end of turn. They're still lands.

{T}: Add {G}.
{1}{G}, {T}: Return target land card from your graveyard to the battlefield tapped.

Trample
When Arpechian Bellowers enters, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Search your library for a green creature card, reveal it, put it into your hand, then shuffle.

Lands you control have hexproof.
{2}{G}{U}: Rouse 2. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

When Arpechian Groundskeeper enters, rouse 1. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)
Remove a +1/+1 counter from Arpechian Groundskeeper: Draw a card.

When Arpechian Stag enters, create a 3/3 red Elk creature token with haste, a 3/3 green Elk creature token with trample, and a 3/3 white Elk creature token with vigilance.

Haste
Whenever Arpechian Tiger attacks, you may sacrifice a land. If you do, Arpechian Tiger deals 3 damage to target creature or planeswalker.

Trample
When Arpechian Yatte enters, put a +1/+1 counter on each other creature you control.
Whenever another creature you control enters, put a +1/+1 counter on Arpechian Yatte.

Flash
When Artisan of Marrow enters, exile another target creature until Artisan of Marrow leaves the battlefield.

{T}: Add one mana of any color. Each other player adds one mana of any color at the beginning of their next first main phase.

Archive 3 (As this enters, shuffle the top three cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever you draw a card from the archived library, put the top card of your main library on the bottom of the archived library.
{R}: Exchange a card from the archived library with a card from your hand.

Flying, double strike
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

When Autumnal Resonants enters, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Create a 3/3 red and green Elemental creature token with haste.

When Banishing Initiate enters, you may exile target nonland permanent you don't control until Banishing Initiate leaves the battlefield.
At the beginning of your end step, sacrifice Banishing Initiate if a card exiled with it has mana value 3 or greater.

When Bestower of Blooms dies, create an X/X green Plant Knight creature token, where X is Bestower of Blooms's power.

Up to two target creatures you control each get +2/+0 and gain first strike and haste until end of turn.
Orchestrate—Tap an untapped red and white creature you control or an untapped red creature you control and untapped white creature you control. (You may exile this card from your hand anytime you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

Target player discards two cards.
Orchestrate {1}{B}{B} (You may exile this card from your hand anytime you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

Rouse 2. Target permanent gains trample until end of turn if it's a creature. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

When Breaker of Secrets enters, each player mills three cards from each of their libraries.
Recite {U} (You may cast this creature from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

Destroy all creatures. Each player shuffles their graveyard into their library.

Draw X cards, then abound. (To abound, you may cast a spell that costs less than this from your hand without paying its mana cost.)

Your life total becomes 0. Until an opponent's next turn, you can't lose the game, your opponents can't win the game, and you can't gain life.
Take an extra turn after this one.
Exile Buy Time.

({T}: Add {W}.)
Bygone Guardian enters tapped.
Vigilance
{2}{W}{W}: Bygone Guardian becomes a creature in addition to its other types until end of turn.

Flying
When Cadre Hawk enters, you may search your library and/or graveyard for a card named Cadre Hawk, reveal it, and put it into your hand. If you searched a library this way, shuffle.