msem-instigator

Germinate, then creatures you control that are Saprolings or have counters on them gain indestructible until end of turn. (To germinate, put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

Whenever you draw a card, put a +1/+1 counter on Ontarachie Curio.
{T}, Remove a +1/+1 counter from Ontarachie Curio: Create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”
{1}{G}: Ontarachie Curio becomes a green 2/1 Dryad creature until end of turn. (It's no longer an artifact.)

Whenever you draw a card, put a +1/+1 counter on Ontarachie Dryad.
Remove a counter from Ontarachie Dryad: Create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”

When Ontarachie Emissary leaves the battlefield, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Vigilance (Attacking doesn't cause this creature to tap.)
Sacrifice a Fungus, Saproling, Plant, or Insect: Put a +1/+1 counter on Ontarachie Forager.

Opalescent Heirloom enters with a charge counter on it for each color of mana spent to cast it.
Equipped creature gets +1/+1 for each charge counter on Opalescent Heirloom.
Equip—{3} or remove a charge counter from Opalescent Heirloom.

{T}: Add {U} or {R}. You lose 1 life unless you have less life than an opponent.

Search your library for a land card, reveal it, then shuffle and put that card on top. (Then exile this card. You may play the land later from exile.)

Whenever Open Road or another permanent you control enters, if it has the greatest mana value among permanents you control, you may discard a card. If you do, draw a card.

At the beginning of your upkeep, each player conjures a card named Data-Point into their hand. (It's a sorcery that costs {2} with “Draw a card.”)

Destroy target artifact. Scry 1.

At the beginning of your upkeep, reveal the bottom card of your library. You may cast it if it's a creature card. Otherwise, exile it.

Opera House enters tapped.
When Opera House enters, add one mana of any color.
{T}, Sacrifice Opera House: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Menace
Whenever Operative GINGER attacks or you cast a blue or white spell, Operative GINGER deals 1 damage to any target.

Ward {3}
Whenever Operative SPORTY attacks or you cast a blue or black spell, put a +1/+1 counter on Operative SPORTY.

Ophan Titan gets +3/+3 as long as there are no nonland cards in your graveyard.
Morph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

When Ophorio Scavenger enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Ophorio Scavenger gets +1/+1 as long as you control three or more artifacts.

{T}: Add {G}. If you control an attacking creature, add one mana of any color instead.

Whenever Oracle of Flames becomes tapped, up to one target creature you control gets +2/-2 until end of turn.

Whenever another nonland permanent you control enters, return that permanent to its owner's hand at the beginning of the next end step.

Whenever you sacrifice an Idol, put a +1/+1 counter on Orchard Botanist.

Whenever Ore Tunneler deals damage to an opponent, tap target land they control. It doesn't untap during its controller's next untap step.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] You may discard a card. If you do, draw a card.
[Lore III] Create a token that's a copy of another target creature you control, except it has haste. Sacrifice it at the beginning of the next end step.

Destroy target artifact or enchantment with mana value 3 or less.
Ferocious — You gain 4 life if you control a creature with power 4 or greater.

Equipped creature gets +1/+1.
Whenever equipped creature deals combat damage to a player, Ornamental Longbow deals 1 damage to any target.
Equip {2}