msem-instigator

Exile up to two target creatures controlled by different players. Return those creatures to the battlefield under their owners' control at the beginning of the next end step.

When Offer the Heart enters, draw a card, then choose a card name.
Whenever a creature with the chosen name dies, you gain 1 life and may draw a card.

Each player sacrifices a creature. If a player lost 3 or more life this turn, each opponent sacrifices a creature instead.

Trample, haste
When Oil Driller enters, salvage two cards at random. (Exile those cards from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)
At the beginning of your end step, sacrifice Oil Driller.

Okrophore's power and toughness are each equal to the number of colorless cards in your graveyard.

Enchant planeswalker
Enchanted planeswalker has “+2: Draw two cards, then put a card from your hand on the bottom of your library.”

Enchant creature or planeswalker
You control enchanted permanent.
Permanents you control but don't own have hexproof.

Archive 4 (As this enters, shuffle the top four cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever you draw a card from the archived library, gain control of target nonland permanent with a lesser mana value than that card until you draw a card from the archived library.

When Okus, the Fabulous Hat enters, gain control of target creature or planeswalker for as long as you control Okus.
[+1]: You may create a blue Aura enchantment token named Fancy Hat with enchant creature and “Enchanted creature gets -2/-0.”
[–2]: Target player loses life equal to the number of enchantments you control and you gain that much life.

When Ol' Sycamore enters, choose up to two —
• Ol' Sycamore fights another target legendary creature.
• Destroy target noncreature storied permanent. (Enchantments and legendary permanents are storied.)

Other Merfolk you control get +1/+1.
When Olantin Pearlreader enters, scry 2. Then draw a card if you control two or more other Merfolk.

Target creature gets -X/-X until end of turn, where X is the number of enchantments you control.

Whenever a creature with power 4 or greater you control enters, it gains haste until end of turn.
{T}: Add {R} or {G}.
{4}{R}{G}: Create a 4/4 red Dragon creature token with flying.

Whenever you cast an instant or sorcery spell from your hand, you may cast target card with the same name as that spell from your graveyard. (You still pay its costs.)

Vigilance
When Olde King Koswe enters, reveal the top eight cards of your library. Put any number of permanent cards from among them onto the battlefield under an opponent's control, then put the rest on the bottom of your library in a random order.
At the beginning of your end step, gain control of target permanent you own.

Oldgrove Nurturer enters with a +1/+1 counter on it.
{G}, Remove a +1/+1 counter from a creature you control: Create a 1/1 colorless Construct artifact creature token.

Flying
Whenever Olson's Armada attacks, if only one creature crewed it, create a 1/1 white Bird creature token with flying. Otherwise, put a +1/+1 counter on Olson's Armada.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Whenever you attack with one or more Pirates, create that many 1/1 white Bird creature tokens with flying that are tapped and attacking. At end of combat, choose one of those tokens, then exile the rest.

Trample, haste
Whenever an opponent casts a noncreature spell, you may return Olten Sandwurm to its owner's hand.

When Olten Surveyor enters, choose any number. Each opponent creates a 1/1 colorless Servo artifact creature token for each mode chosen.
• Destroy target artifact or enchantment with mana value 3 or less.
• Shuffle up to four cards from target player's graveyard into their library.
• You gain 4 life.

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.

At the beginning of your upkeep, create four 1/1 blue Elemental creature tokens with flying. You gain 4 life.
{2}{W}, Discard Olten's Farewell: Create two 1/1 blue Elemental creature tokens with flying. You gain 2 life.

{T}: Add {C}.
{6}, {T}, Discard a card: Search your library for a multicolored card, exile it, then shuffle. If its mana value is 3 or less, you may cast it without paying its mana cost. If you don't, put it into your hand. Activate only as a sorcery.

Whenever you cast a noncreature spell, Omegalomania deals 2 damage to any target. Whenever a permanent you don't control dealt damage this way dies this turn, return it to the battlefield tapped under your control.

Play with the top card of your library revealed.
Whenever you draw a card, destroy each creature with the same mana value as that card.