Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Whenever Odylic Wraith deals damage to a player, that player discards a card.

This spell costs less to cast if you control a Human creature and a non-Human creature.

Draw two cards.

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."

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

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

Whenever another nontoken creature dies, you may create a 1/1 black Rat creature token.

Rats you control have deathtouch.

Trample

If a red source you control would deal an amount of noncombat damage less than Ojer Axonil's power to an opponent, that source deals damage equal to Ojer Axonil's power instead.

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

Flying

Whenever you cast an instant spell from your hand, it gains rebound. (Exile it as it resolves. At the beginning of your next upkeep, you may cast it from exile without paying its mana cost.)

When Ojer Pakpatiq dies, return it to the battlefield tapped and transformed under its owner's control with three time counters on it.

When Oji, the Exquisite Blade enters, you gain 2 life and scry 2.

Whenever you cast your second spell each turn, exile up to one target creature you control, then return it to the battlefield under its owner's control.

O-Kagachi Made Manifest is all colors.

Flying, trample

Whenever O-Kagachi Made Manifest attacks, defending player chooses a nonland card in your graveyard. Return that card to your hand. O-Kagachi Made Manifest gets +X/+0 until end of turn, where X is the mana value of that card.

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

I, II — Each opponent loses 1 life and you gain 1 life.

III — Exile this Saga, then return it to the battlefield transformed under your control.

At the beginning of combat on your turn, Oko, the Ringleader becomes a copy of up to one target creature you control until end of turn, except he has hexproof.

+1: Draw two cards. If you've committed a crime this turn, discard a card. Otherwise, discard two cards.

−1: Create a 3/3 green Elk creature token.

−5: For each other nonland permanent you control, create a token that's a copy of that permanent.

Flying

At the beginning of each end step, if a creature died this turn, create a Food token. (It's an artifact with ", , Sacrifice this artifact: You gain 3 life.")

, Sacrifice another creature or artifact: Old Flitterfang gets +2/+2 until end of turn.

, : Tap target creature without reminder text. (Reminder text is still any italicized text in parentheses that explains rules you already know.)

Old Man Willow's power and toughness are each equal to the number of lands you control.

Whenever Old Man Willow attacks, you may sacrifice another creature or a token. When you do, target creature an opponent controls gets -2/-2 until end of turn.

When Old Rutstein enters and at the beginning of your upkeep, mill a card. If a land card is milled this way, create a Treasure token. If a creature card is milled this way, create a 1/1 green Insect creature token. If a noncreature, nonland card is milled this way, create a Blood token.

Flying

Old-Fashioned Vampire gets +2/+2 and has deathtouch as long as it's dark outdoors.

Old-Growth Grove enters tapped.

: Add or .

Flying

: Olivia Voldaren deals 1 damage to another target creature. That creature becomes a Vampire in addition to its other types. Put a +1/+1 counter on Olivia Voldaren.

: Gain control of target Vampire for as long as you control Olivia Voldaren.

Flying

Whenever another creature you control enters, you may discard a card. If you do, put a +1/+1 counter on that creature, it gains haste until end of turn, and it becomes a Vampire in addition to its other types.

Flying

Olivia's Bloodsworn can't block.

: Target Vampire gains haste until end of turn.

Target creature gets -2/-2 until end of turn. If it's night, that creature gets -13/-13 until end of turn instead.

Flash

When Omen of the Dead enters, return target creature card from your graveyard to your hand.

, Sacrifice Omen of the Dead: Scry 2.

Return target card from your graveyard to your hand. Put up to one other target card from your graveyard on top of your library. Exile Once and Future.

Adamant — If at least three green mana was spent to cast this spell, instead return those cards to your hand and exile Once and Future.

Whenever Ondu Cleric or another Ally you control enters, you may gain life equal to the number of Allies you control.

First strike

Landfall — Whenever a land you control enters, Ondu Greathorn gets +2/+2 until end of turn.

Lifelink

Whenever another modified creature you control dies, put two +1/+1 counters on Ondu Knotmaster.

Ondu Skyruins enters tapped.

: Add .

Cohort — , Tap an untapped Ally you control: You gain 2 life.

Enchant creature

Enchanted creature can't attack or block, and its activated abilities can't be activated.

At the beginning of the upkeep of enchanted creature's controller, that player loses 1 life.

Enchant creature

Enchanted creature gets +2/+2 and has flying.

Defender

Creatures with flying your opponents control get -1/-0.

Target creature gets +X/+0 until end of turn, where X is its power.

Defender, flying

Wither (This deals damage to creatures in the form of -1/-1 counters.)

When an opponent casts a creature spell, if Opal Caryatid is an enchantment, Opal Caryatid becomes a 2/2 Soldier creature.

Defender (This creature can't attack.)

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)

: The next time a source of your choice would deal damage this turn, that damage is dealt to Opal-Eye, Konda's Yojimbo instead.

: Prevent the next 1 damage that would be dealt to Opal-Eye this turn.

Whenever Ophidian attacks and isn't blocked, you may draw a card. If you do, Ophidian assigns no combat damage this turn.

Flying

When Opportunistic Dragon enters, choose target Human or artifact an opponent controls. For as long as Opportunistic Dragon remains on the battlefield, gain control of that permanent, it loses all abilities, and it can't attack or block.

Devoid (This card has no color.)

, Put a card an opponent owns from exile into that player's graveyard: Draw a card, then discard a card.

When Oracle of Tragedy enters or dies, choose one —

• Draw a card, then discard a card.

• Shuffle up to four target cards with mana value 3 or greater from your graveyard into your library.

Trample

Landfall — Whenever a land you control enters, put a +1/+1 counter on Oran-Rief Hydra. If that land is a Forest, put two +1/+1 counters on Oran-Rief Hydra instead.

Protection from red

, : Add two mana in any combination of colors. Spend this mana only to cast Dragon spells or activate abilities of Dragons.

, , Sacrifice Orb of Dragonkind: Look at the top seven cards of your library. You may reveal a Dragon card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

You have hexproof. (You can't be the target of spells or abilities your opponents control.)

If a creature would deal damage to you, prevent 1 of that damage.

Council's dilemma — When Orchard Elemental enters, starting with you, each player votes for sprout or harvest. Put two +1/+1 counters on Orchard Elemental for each sprout vote. You gain 3 life for each harvest vote.

When Orchard Strider enters, create two Food tokens. (They're artifacts with ", , Sacrifice this artifact: You gain 3 life.")

Basic landcycling (, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

, Sacrifice a creature: Orcish Bloodpainter deals 1 damage to any target.

Target creature gains your choice of lifelink or indestructible until end of turn.

Amass Orcs 1. (Put a +1/+1 counter on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.)

Flying, trample

When Orcus, Prince of Undeath enters, choose one —

• Each other creature gets -X/-X until end of turn. You lose X life.

• Return up to X target creature cards with total mana value X or less from your graveyard to the battlefield. They gain haste until end of turn.