If you control a commander, you may cast this spell without paying its mana cost.

Prevent all damage that would be dealt this turn by creatures your opponents control.

If it's neither day nor night, it becomes day as Obsessive Astronomer enters.

Whenever day becomes night or night becomes day, discard up to two cards, then draw that many cards.

Draw a card.

Madness (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

: Draw a card, then discard a card.

, , Sacrifice Obsessive Stitcher: Return target creature card from your graveyard to the battlefield.

Protection from black

: Target creature gains protection from black until end of turn.

This spell costs less to cast for each land your opponents control that could produce .

Flying

When Obsidian Charmaw enters, destroy target nonbasic land an opponent controls.

When Obstinate Baloth enters, you gain 4 life.

If a spell or ability an opponent controls causes you to discard Obstinate Baloth, put it onto the battlefield instead of putting it into your graveyard.

Obstinate Gargoyle has flying as long as it's modified. (Equipment, Auras you control, and counters are modifications.)

Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Flash

Flying

Whenever another Faerie you control enters, each opponent loses 1 life.

When Obzedat, Ghost Council enters, target opponent loses 2 life and you gain 2 life.

At the beginning of your end step, you may exile Obzedat. If you do, return it to the battlefield under its owner's control at the beginning of your next upkeep. It gains haste.

Draw X cards, then discard X cards. Create a 1/1 white Spirit creature token with flying for each card type among cards discarded this way.

First strike, lifelink

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)

At the beginning of your end step, if you gained life this turn, create a 1/1 white Cat creature token. Then if you have the city's blessing, for each token you control that entered this turn, create a token that's a copy of it.

Trample

Ochre Jelly enters with X +1/+1 counters on it.

Split — When Ochre Jelly dies, if it had two or more +1/+1 counters on it, create a token that's a copy of it at the beginning of the next end step. The token enters with half that many +1/+1 counters on it, rounded down.

When Octo Opus enters, create a 4/4 blue Octopus Performer creature token named Contortionist with "At the beginning of your upkeep, you may fold this token in half." (It becomes 2/2, then 1/1, ½/½, and so on.)

Sacrifice Octo Opus: Draw a card and an additional card for each of Contortionist's folds.

When Octoprophet enters, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Enchant creature

Enchanted creature has ": Draw a card."

: Enchanted creature gains vigilance until end of turn.

Flying

As long as you control a transformed permanent, Oculus Whelp has "When Oculus Whelp dies, draw a card."

At the beginning of each combat, creatures you control gain banding until end of turn if a creature you control has banding. The same is true for changeling, devoid, fear, flanking, horsemanship, ingest, intimidate, landwalk, shroud, tantrum, wither, and the activated ability "Sacrifice this creature: Add ."

: Regenerate Odious Trow.

When Odric, Blood-Cursed enters, create X Blood tokens, where X is the number of abilities from among flying, first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance found among creatures you control. (Count each ability only once.)

First strike (This creature deals combat damage before creatures without first strike.)

Whenever Odric, Master Tactician and at least three other creatures attack, you choose which creatures block this combat and how those creatures block.

When Odunos River Trawler enters, return target enchantment creature card from your graveyard to your hand.

, Sacrifice Odunos River Trawler: Return target enchantment creature card from your graveyard to your hand.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)

I — Put a +1/+1 counter on up to one target creature. Create a Food token.

II — Draw a card. Create a Food token.

III — Create a 1/1 white Halfling creature token for each Food you control.

Target creature can't attack or block this turn.

Disguise (You may cast this card face down for as a 2/2 creature with ward . Turn it face up any time for its disguise cost.)

When Offender at Large enters or is turned face up, up to one target creature gets +2/+0 until end of turn.

Counter target spell unless its controller pays . You gain 4 life.

At the beginning of combat on your turn, exile target red, white, or black creature card from your graveyard. Create a token that's a copy of that card, except it's 1/1. It gains haste until your next turn.

At the beginning of your upkeep, look at the top two cards of your library, then put one of them into your graveyard.

Whenever a creature card is put into your graveyard from your library or hand, it perpetually gains "When this card leaves your graveyard, create a tapped 2/2 black Zombie creature token."

When Ogre Arsonist enters, destroy target land.

Whenever another creature you control enters, that creature gets +2/+0 and gains haste until end of turn. (It can attack and this turn.)

Menace

Whenever Ogre Chitterlord enters or attacks, create two 1/1 black Rat creature tokens with "This creature can't block." Then if you control five or more Rats, each Rat you control gets +2/+0 until end of turn.

Whenever Ogre Errant attacks, another target attacking Knight gains menace until end of turn. (It can't be blocked except by two or more creatures.)

Whenever Ogre Geargrabber attacks, gain control of target Equipment an opponent controls until end of turn. Attach it to Ogre Geargrabber. When you lose control of that Equipment, unattach it.

Whenever Ogre Leadfoot becomes blocked by an artifact creature, destroy that creature.

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

: Ogre Menial gets +1/+0 until end of turn.

Defender

: Destroy target creature that was dealt damage this turn.

Ogre Taskmaster can't block.

Equipped creature gets +2/+2.

Whenever Ogre-Head Helm or equipped creature deals combat damage to a player, you may sacrifice it. If you do, discard your hand, then draw three cards.

Reconfigure (: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Reach

Untap all Archers you control during each other player's untap step.

Whenever an Archer you control deals damage to a creature, you may pay . If you do, draw a card.

Whenever Ohran Viper deals combat damage to a creature, destroy that creature at end of combat.

Whenever Ohran Viper deals combat damage to a player, you may draw a card.

When Oil-Gorger Troll enters, you gain 3 life. Then if you control a permanent with an oil counter on it, draw a card.

Trample

Whenever Ojer Kaslem deals combat damage to a player, reveal that many cards from the top of your library. You may put a creature card and/or a land card from among them onto the battlefield. Put the rest on the bottom in a random order.

When Ojer Kaslem dies, return it to the battlefield tapped and transformed under its owner's control.

Vigilance

If one or more creature tokens would be created under your control, three times that many of those tokens are created instead.

When Ojer Taq dies, return it to the battlefield tapped and transformed under its owner's control.

Whenever you cast a noncreature spell, choose one —

• Tap target creature.

• Ojutai Exemplars gains first strike and lifelink until end of turn.

• Exile Ojutai Exemplars, then return it to the battlefield tapped under its owner's control.

: Add or .

: Ojutai Monument becomes a 4/4 white and blue Dragon artifact creature with flying until end of turn.

Tap target creature. It doesn't untap during its controller's next untap step.

Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Create a 2/2 blue Djinn Monk creature token with flying.

Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)