msem-instigator

Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)
Creatures with power less than Olten Survivalist's power can't block creatures you control.

Flash
When Olten Vipermoa enters, you may return another creature you control to its owner's hand. If you do, put two +1/+1 counters on Olten Vipermoa.

Target creature gets -5/-5 until end of turn. Scry 1.

You may have Omendancer enter as a copy of a creature you control or a Curse you control. (If it copies a double-faced permanent, it can't transform.)

Colossal 3—{5}{U} (You may cast this for its colossal cost to have it enter with three +1/+1 counters; or pay {5}{U} as a sorcery: Put three +1/+1 counters on it if it has none.)
When Omendiver's colossal ability puts one or more counters on it, scry 3.

Ominous Dragoncaller gets +1/+1 and has flying as long as you control a Dragon.

Equipped creature gets +0/+3 and has menace. (It can't be blocked except by two or more creatures.)
Equip {1}

Post a bounty on target creature you don't control, then each opponent sacrifices a creature. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)

I, II — Put your choice of a flying or hexproof counter on target creature you control.
III — Creatures you control with counters on them can't be blocked this turn unless defending player pays {3} and spells that target those creatures cost an additional {3} to cast until your next turn.
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Whenever a creature dies, put a +1/+1 counter on each creature you control with power less than it.
{3}{G}, Sacrifice a creature: Draw cards equal to the sacrificed creature's power.

This spell costs {G} less to cast if it targets a blue or black permanent.
Destroy target artifact, enchantment, or planeswalker.

This spell costs {W} less to cast if it targets a black or red permanent.
Exile target nonland permanent with mana value 3 or less.

Gain control of target creature until end of turn and untap it. Until end of turn, it gains haste and “Whenever this creature attacks, it deals 2 damage to itself.”

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.”)