msem-instigator

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

Whenever Orria Mirrorpelt becomes the target of a spell, exile that spell. If Orria Mirrorpelt was its only target, copy it for each other creature target player controls. Each copy targets a different one of those creatures.

Pressure {3}{B} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
When Oryxyth's Brood enters, you draw two cards and you lose 2 life.

Pressure—{4}{U}{B}, Sacrifice two creatures. (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Whenever Oryxyth enters or attacks, create an X/X black Horror creature token, where X is the number of cards in your graveyard.
{U}{B}, Sacrifice another creature: Gain control of target creature with power less than the sacrificed creature's power.

Flying, vigilance
Orzhov Benefactor can't attack or block unless you pay {1} for each debt counter on it.
At the beginning of your upkeep, put a debt counter on Orzhov Benefactor.
{2}: Remove a debt counter from Orzhov Benefactor.

Flash
Oscanthor, Trader's Ruin can't be blocked.
Whenever a creature you control deals combat damage to a player, draw a card.

{T}, Discard a card: Draw a card.
{2}{R}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy. Activate only if you have four or more instant and/or sorcery cards in your graveyard.

Flying
Whenever an opponent casts a spell, counter it unless that player pays {1} for each spell cast before it this turn.

Flash
Flying
When Oshin enters, counter target spell if its mana value is less than or equal to the number of spells you've cast this turn.

Oshiruko Whisperwalker can't be blocked except by Rogues.
Whenever a creature is returned to its owner's hand, you may draw a card. If you do, discard a card.

Trample
Whenever Oshu deals combat damage to a player, gain control of target land that player controls. It becomes a 4/4 Elemental creature that's still a land.
As long as you control eight or more lands, Oshu and land creatures you control get +2/+2.

{8}: Create eight 1/1 blue Tentacle creature tokens.
{8}: Counter target spell unless its controller pays {8}.
{8}: Draw eight cards.

When Ostracizer Orb enters, exile target nonartifact, nonland permanent until Ostracizer Orb leaves the battlefield.

Lifelink
{2}{B}: Create a 1/1 black Human Warlock creature token with lifelink.
{4}{B}{B}{B}, Pay 7 life: Transform Oswin, Skirsdag Diabolist.

Exile any number of target creatures you control. At the beginning of the next end step, return to the battlefield tapped each creature card exiled this way and each creature card put into your graveyard from the battlefield this turn.

Whenever you cast a noncreature spell, up to one target artifact or non-Aura enchantment you control becomes a 3/3 creature in addition to its other types until end of turn.

Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Exile target creature. That creature's controller creates a 1/1 blue Elemental creature token with flying.

Flying
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Whenever Outrider Captain attacks, search your library for a creature card with mana value 1 or less, put it onto the battlefield tapped and attacking, then shuffle.

Counter target spell if you have more cards in hand than its controller.

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

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Over the Moon deals 4 damage to up to one target creature or planeswalker.
II, III — Until end of turn, spells you cast with mana value 4 or greater cost {1} less to cast and can't be countered.
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Enchant player
Whenever enchanted player becomes the target of a spell or ability they don't control, if it isn't a copy, its controller copies it.

Whenever you cast an instant or sorcery spell, copy it. You may choose new targets for the copy. Overclock deals X damage to you, where X is the number of spells you've cast this turn.

Until end of turn, creatures you control have base power X/Y, where X is the greatest base power among creatures you control and Y is the greatest base toughness among creatures you control.
If you control a creature with flying, creatures you control gain flying until end of turn. The same is true for first strike, haste, lifelink, menace, prowess, trample, and vigilance.