msem-instigator

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.”

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

When Onward to War enters, draw a card, then choose a card name.
Whenever one or more creatures you control with the chosen name attack, look at the top four cards of your library. Put a creature or enchantment card with mana value 3 or less from among them into your hand. Put the rest on the bottom of your library in any order.

Lifelink
Whenever a planeswalker dies, Onya's Chosen deals 3 damage to target creature or player.

Archive 6 (As this enters, shuffle the top six cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever a creature or planeswalker you control dies, you may play a card from the archived library. (You still pay its costs.)

Flying
Spells your opponents cast cost an additional 2 life to cast.

Deathtouch
Whenever Oozing Adder attacks, you may have target creature defending player controls block it this combat if able.

For each nonland token you control, create a token that's a copy of it.

Exile two target permanents you control, then return them to the battlefield under your control.

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
When Ophelia's Neophyte enters, you may have another target creature you control gain lifelink until end of turn.

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.

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.

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

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.

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 you cast a black spell, choose up to X, where X is the number of black mana symbols in that spell's mana cost —
• Target player loses 1 life and you gain 1 life.
• Put a -1/-1 counter on target creature.
• You draw a card and you lose 3 life.
• Exile target card in a graveyard.

Your opponents play with the top card of their library revealed.
Your opponents can't cast spells during your turn.
You may play lands and cast spells from the top of an opponent's library during your turn.

Draw two cards. Create a tapped colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”

Pressure—Reappropriate black. (You may cast this spell by exiling two black cards from your hand and/or graveyard if there are seven or more cards in your graveyard.)
Destroy target creature or planeswalker.

Whenever Orphan Prodigy is dealt damage, it deals that much damage to target player.
Attain {4}{R} ({4}{R}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Vigilance
You may look at the top card of your library any time.
Whenever you cast a creature spell from your hand, you may cast the top card of your library without paying its mana cost if it's a creature card with lesser mana value.

Whenever you make first contact, Oscuran Wingmate gains flying until end of turn. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Flying
Whenever an opponent casts a spell, counter it unless that player pays {1} for each spell cast before it this turn.