msem-instigator

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.)

{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.

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

Ominous Lair enters tapped unless you have 15 or less life.
{T}: Add {W} or {B}.

{T}: Add {U} or {B}. You lose 1 life unless you have less life than an opponent.

Ominous Quag enters tapped.
{T}: Add {W} or {B}.
{2}{W}{B}, {T}, Sacrifice Ominous Quag: Draw a card.

Onoran Runeglyphs enters tapped.
{T}: Add two mana in any combination of colors from among creatures you control.
Menagerie — {2}, {T}: Draw a card. Activate only if there are five or more creature types among creatures you control.

{T}: Add {U} or {R}. You lose 1 life unless you have less life than an opponent.

At the beginning of your upkeep, each player conjures a card named Data-Point into their hand. (It's a sorcery that costs {2} with “Draw a card.”)

Opera House enters tapped.
When Opera House enters, add one mana of any color.
{T}, Sacrifice Opera House: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Whenever Optimistic Chronicler deals damage to a player or noncreature permanent, surveil 1, then draw a card.

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

Equipped creature gets +1/+1.
Whenever equipped creature deals combat damage to a player, Ornamental Longbow deals 1 damage to any target.
Equip {2}

Ornamented Evergreen enters tapped unless you have two or more opponents.
{T}: Add {G} or {W}.

{1}, Sacrifice Ornate Incense: Draw a card. You gain 1 life.

All creatures able to block Orphaned Nuckalavee do so.

You may cast spells as though they had flash.

At the beginning of your upkeep, scry 1, then you gain 1 life.

({T}: Add {G}.)
Wanderlust — Otherworldly Forest enters tapped unless you control four or more other differently named lands.
{1}, {T}: Add one mana of any color.

({T}: Add {U}.)
Wanderlust — Otherworldly Island enters tapped unless you control four or more other differently named lands.
{1}, {T}: Add one mana of any color.

({T}: Add {R}.)
Wanderlust — Otherworldly Mountain enters tapped unless you control four or more other differently named lands.
{1}, {T}: Add one mana of any color.

({T}: Add {W}.)
Wanderlust — Otherworldly Plains enters tapped unless you control four or more other differently named lands.
{1}, {T}: Add one mana of any color.

({T}: Add {B}.)
Wanderlust — Otherworldly Swamp enters tapped unless you control four or more other differently named lands.
{1}, {T}: Add one mana of any color.

Enchant player
At the beginning of your upkeep, enchanted player loses 1 life.

When Over the Horizon enters, scry 1.
{T}: Add {C}.
{1}, {T}: Return Over the Horizon to its owner's hand.