msem-instigator

As Ocean Monastery enters, you may pay 2 life. If you don't, Ocean Monastery enters tapped.
{T}, Sacrifice Ocean Monastery: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Whenever one or more artifacts you control enter, put a +1/+1 counter on Octopus Shiny-Grabber and you gain 1 life.

Ode to the Red Wind deals 1 damage to target creature. It can't block this turn.
Showcase {3}{R} (Then if you cast this for its showcase cost, create a 1/1 red Bard creature token that can't block and exile this. Whenever it attacks, you may cast a free copy of this.)

You may pay {R} and tap an untapped Warrior you control rather than pay this spell's mana cost.
Choose one —
• Double the power of target creature you control until end of turn.
• Target creature you control deals damage equal to its power to target creature or planeswalker.

Destroy target artifact or enchantment. Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

{T}: You may put a land card from your hand onto the battlefield.
{1}, {T}: Aetherize target land you control. (To aetherize, create a token that's a copy of it, then exile that token.)

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.

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.)

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.

{2}, {T}, Sacrifice Old Map: Search your library for a basic land card, put it onto the battlefield, then shuffle.

Defender, flying
Menagerie — As long as there are five or more creature types among creatures you control, Old-Rune Sentinel can attack as though it didn't have defender.

Flying
Menagerie — When Old-Rune Watcher enters, if there are five or more creature types among creatures you control, draw a card.

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.

Haste (This creature can attack and {T} as soon as it comes under your control.)
Olson's Sky Brigade has flying as long as you control another attacking Pirate.

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.

Trample
Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)
Cycling {2} ({2}, Discard this card: Draw a card.)

{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.

Reach
When Oltenen Terror enters, crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)
{1}{G}, Sacrifice an artifact or creature: Tap Oltenen Terror. It gains indestructible until end of turn.

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}