msem-instigator

(Activate each submodule once as a sorcery. When this enters, activate one submodule for free.)
{G}{G}{G}: Seed
Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.
{G}{G}{G}: Soil
Destroy target noncreature permanent.
{G}{G}{G}: Stem
Root Module gains “You may play an additional land on each of your turns.” and “Lands you control are every basic land type in addition to their other types.”

Once each turn, when Rova, the Fleshweaver enters or you attack with one or more Horrors, you may put a +1/+1 counter on each creature you control. Then if Rova isn't a token, untap each land you control. Until your next turn, you may cast permanent spells as though they had flash.
{2}{G}{G}, Discard Rova: Create a token that's a copy of Rova, the Fleshweaver, except it's 4/4 and isn't legendary. Activate only as a sorcery.

You may spend mana as though it were mana of any color to cast spells with mana value 5 or greater or to activate abilities of permanents or permanent cards with mana value 5 or greater.
{T}: Add {C}.

Look at the top six cards of your library. Put up to two creature cards with total mana value 4 or less from among them onto the battlefield and the rest on the bottom of your library in any order.
Ferocious — If you control a creature with power 4 or greater, put a +1/+1 counter on each creature you control.

Trample, ward {1}
Whenever Stardust Surveyor deals combat damage to a player, you may mill cards until you mill a creature card. When you do, return target creature card from your graveyard to your hand.

If you've lost life this turn, you may cast this spell as though it had flash.
Return X target cards with different mana values from your graveyard to your hand. Put Studies Past on the bottom of its owner's library.

{T}: Add {G}. Spend this mana only to cast a creature spell or activate an ability of a creature.
At the beginning of combat on your turn, if you control a creature with power 4 or greater, Vassal of the Wild gets +2/+1 and gains vigilance until end of turn.

You may play basic land cards you own from outside the game.

Choose one —
• Destroy target artifact or enchantment with mana value 3 or less.
• You gain 3 life. Draw a card.

Legacy (You may play this side of this card only from your graveyard. Exile it if it would leave the battlefield or not resolve.)
At the beginning of your end step, you may search your library for a creature card, reveal it, put it into your hand, then shuffle.

[+1]: Mill four cards, then return up to one creature card milled this way to your hand. You may activate a different loyalty ability Vivien has this turn.
[+1]: Create a 2/2 green Cat Spirit creature token with “When this creature dies, you gain 2 life.”
[–3]: Choose target creature you don't control. If it has flying, destroy it. Otherwise, up to one target creature you control deals damage equal to its power to that creature.
[–9]: Create four 4/4 green Hydra creature tokens. Creatures you control gain trample and haste until end of turn.

[+1]: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
[–3]: You get an emblem with “{1}{G}: You may play an additional land this turn.”
[–6]: Creatures you control gain trample and have base power and toughness X/X until end of turn, where X is the number of lands you control.

Vigilance
Whenever Warfield Excavator attacks, you may exile target card from a graveyard.
Warfield Excavator gets +1/+1 for each card type among cards exiled with it.

(Choose only one work as a sorcery to add its ability.)
When Wildlife Sketches enters, reveal the top five cards of your library. Put a creature card from among them into your hand and the rest on the bottom in any order.
{1}{G}: Carnation Petals
You may cast creature spells as though they had flash.
{3}{G}: Pecking Order
At the beginning of your upkeep, you may sacrifice a creature. If you do, search your library for a creature card with mana value equal to 1 plus the sacrificed creature's mana value, put it onto the battlefield, then shuffle.

Ferocious — Once each turn, when a creature you control with power 4 or greater enters, you may untap all lands you control.

{1}{G}: Create a 1/1 colorless Construct artifact creature token.
{2}{G}{G}: Target creature you control becomes 4/4. (This lasts indefinitely.)
{4}{G}{G}{G}{G}: Put four +1/+1 counters on each creature you control with power 4 or greater.

{T}: Add {C}.
{T}, Sacrifice a creature: Add one mana of any color.

If a creature entering under you control causes an ability to trigger, you may pay -1. Whenever you do, copy that ability. You may choose new targets for the copy.
[+1]: Exile target creature. Return that card to the battlefield tapped under its owner's control at the beginning of the next end step. If you don't control it, it enters with a stun counter.
[–2]: Draw a card and gain 2 life.

Whenever a creature attacks you, tap that creature. It doesn't untap during its controller's next untap step.

Counter target spell. If a noncreature spell is countered this way, conjure a card named Fatigue and put it on top of your library. (It's a colorless sorcery that costs {2} with “Draw a card.”)

Target opponent reveals their hand. You choose a nonland card from it. That player discards that card.
Create a Function token with “Draw a card if a player discarded a card this turn.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Whenever you cast your second spell during each of your turns, you may activate one of Salome's loyalty abilities.
[+1]: Draw a card. Untap up to two lands.
[–4]: Destroy all creatures.
[–8]: You get an emblem with “You may pay {0} rather than pay the mana cost for the second spell you cast each turn.”

[+2]: You may discard a card. If you do, draw two cards.
[–3]: Return target creature card from your graveyard to the battlefield. It gains haste. Return it to your hand at the beginning of the next end step.
[–7]: Discard your hand, then draw seven cards. You may put an Edarna planeswalker card from your hand or graveyard onto the battlefield.

First strike
Whenever Ogura, Contracted Rebel attacks, you may create a token that's a copy of another attacking creature with power less than or equal to Ogura's. Sacrifice the token at the beginning of your next end step.
{R}: Ogura gets +1/+0 until end of turn.

Flying, haste
Whenever another creature dies, Twinfire Dragon gets +1/+0 until end of turn.