msem-instigator

{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.

Opalescent Heirloom enters with a charge counter on it for each color of mana spent to cast it.
Equipped creature gets +1/+1 for each charge counter on Opalescent Heirloom.
Equip—{3} or remove a charge counter from Opalescent Heirloom.

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

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.

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.

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.

Overgrown Enclave enters tapped.
{T}: Add {G} or {U}.
{4}{G}{U}: Until end of turn, Overgrown Enclave becomes a Turtle creature with ward {2} in addition to its other types.
Scavenge {5}{G}{U}

{T}, Pay 1 life: Add {G} or {W}.
{1}, {T}, Sacrifice Overgrown Refuge: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Overgrown Ruins enters tapped.
As Overgrown Ruins enters, choose a color other than green.
{T}: Add {G} or one mana of the chosen color.

Whenever Overgrowth Host attacks, germinate. Then creatures you control that are Saprolings or have counters on them gain trample until end of turn.
Saprolings you control get +1/+1.

{T}: Add {C}.
{7}, {T}: Copy target instant or sorcery spell with {X} in its mana cost. You may choose new targets for the copy. This ability costs {1} less to activate for each instant and sorcery card in your graveyard.

(Transform this if it's not attached to a creature. Pay {G} as a sorcery to unattach it.)
Enchant creature you control
When this permanent transforms into Packbond Mount, move all +1/+1 counters from it to its rider.
Packbond Mount's rider gets +1/+1.
{2}{G}: Put a +1/+1 counter on Packbond Mount's rider.

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Palace Hall enters tapped.
When Palace Hall enters, look at the top card of your library. You may put it into your graveyard.
{T}: Add {G} or {W}.

{T}, Sacrifice Palace of Reflections: Choose a land you control. Search your library for a land card with the same name as the chosen land, put it onto the battlefield tapped, then shuffle.