msem-instigator

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.

Voracious 2 (As this enters, you may sacrifice up to two artifacts and/or creatures. This creature enters with that many +1/+1 counters on it.)
When Opportunistic Beast enters, destroy up to one target creature that was dealt damage this turn.

Target creature gets -4/-4 until end of turn.
Civilized — Draw a card if you control an artifact, a creature, and an enchantment.

Enchant creature
Enchanted creature can't attack or block unless its controller pays {3}.
Activated abilities of enchanted creature cost {3} more to activate.

Creatures can't attack you unless their controller pays {3} for each of those creatures.

Scry 1.
Draw a card.

Whenever you cast your first instant or sorcery spell each turn, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

When Opulent Proprietor enters, you may search your library and/or graveyard for an Aura, Aurashaper, Equipment, or Vehicle card, reveal it, and put it into your hand. If you search your library this way, shuffle.

Draw three cards, then discard two cards.

When Oracle Crab enters, scry 2. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)

When Oracle of Edicts enters, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Whenever an Aura you control enters, scry 1.

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

Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on Oracle of Tides.

Whenever you cast a noncreature spell, creatures you control get +1/+1 until end of turn.

Enchant creature
Enchanted creature gets -3/-3.
When enchanted creature dies, its controller may scry 1.

Each player mills three cards.
Draw a card.

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

Ward—Pay 2 life.
When Orchid Suit enters, target opponent reveals their hand, then exiles a nonland card of their choice from it until Orchid Suit leaves the battlefield.

Target creature gets -5/-5 until end of turn.
Judge up to one target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)

Identity — When Order's Anointer enters, if you control at least two other creatures that share a creature type with it, creatures you control get +1/+1 until end of turn.

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.

Oreskos Warden has lifelink as long as you control an enchantment.

Whenever Organ Scavenger perseveres, each opponent loses 2 life. (A creature perseveres when it survives damage.)