+1: Put two +1/+1 counters on up to one target creature you control.

0: Until end of turn, Oko, the Trickster becomes a copy of target creature you control. Prevent all damage that would be dealt to him this turn.

−7: Until end of turn, each creature you control has base power and toughness 10/10 and gains trample.

When Ol' Buzzbark enters the battlefield, roll X six-sided dice onto the battlefield from a height of at least X inches. For each die, put a number of +1/+1 counters equal to the result on each creature you control that die is touching. For each die, Ol' Buzzbark deals damage equal to the result to each creature an opponent controls that die is touching.

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.)

When you cast this spell, reveal cards from the top of your library until you reveal X creature cards. Put all creature cards revealed this way into your graveyard, then put the rest on the bottom of your library in a random order.

Old Stickfingers's power and toughness are each equal to the number of creature cards in your graveyard.

When Old-Growth Dryads enters the battlefield, each opponent may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.

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 enters the battlefield under your control, 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.

Discard a card: Olivia's Dragoon gains flying until end of turn.

Vigilance

Sacrifice Ollenbock Escort: Target creature you control with a +1/+1 counter on it gains lifelink and indestructible until end of turn.

Each opponent exiles a creature with the greatest power among creatures that player controls.

Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, Olórin's Searing Light deals damage to each opponent equal to the power of the creature they exiled.

When Oltec Archaeologists enters the battlefield, choose one —

• Return target artifact card from your graveyard to your hand.

• Scry 3. (Look at the top three cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Whenever you cast a creature spell, choose one —

• Create a 1/1 colorless Gnome artifact creature token.

• Create a token that's a copy of target artifact token you control.

Return all Islands to their owners' hands. Each player sacrifices a Plains or a white permanent for each white permanent they control.

When Omenpath Journey enters the battlefield, search your library for up to five land cards that have different names, exile them, then shuffle.

At the beginning of your end step, choose a card at random exiled with Omenpath Journey and put it onto the battlefield tapped.

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

, , Sacrifice Ominous Parcel: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

, , Sacrifice Ominous Parcel: It deals 4 damage to target creature.

When Ominous Traveler enters the battlefield, draft a card from Ominous Traveler's spellbook. That card perpetually gains "You may spend mana as though it were mana of any color to cast this spell" and "When you cast this spell, return a creature named Ominous Traveler you control to its owner's hand."

Landfall — Whenever a land enters the battlefield under your control, create a 5/5 red and green Elemental creature token.

Whenever Omnath, Locus of Rage or another Elemental you control dies, Omnath deals 3 damage to any target.

Target creature gets +2/+2 until end of turn. Untap it. (Then exile this card. You may cast the creature later from exile.)

Whenever you draw your second card each turn, you may put a land card from your hand onto the battlefield tapped.

Creatures can't attack planeswalkers you control unless their controller pays for each creature they control that's attacking a planeswalker you control.

, Exile Onakke Oathkeeper from your graveyard: Return target planeswalker card from your graveyard to the battlefield.

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 enters the battlefield under your control, you may gain life equal to the number of Allies you control.

Destroy all nonland permanents.

Ondu Skyruins enters the battlefield tapped.

: Add .

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

Enchant creature

Whenever enchanted creature deals combat damage to a player, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Enchant creature or enchantment

Enchanted permanent is an enchantment and loses all other card types. (It still has its abilities, but it's no longer a creature.)

Flying

Whenever you draw a card, put a +1/+1 counter on Oneirophage.

Flying

Each other Rogue creature you control enters the battlefield with an additional +1/+1 counter on it.

Whenever a creature you control with a +1/+1 counter on it deals combat damage to a player, that player discards a card.

Target player draws a card.

Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

, Sacrifice a non-Ooze creature: Create an X/X green Ooze creature token, where X is the sacrificed creature's power. Activate only as a sorcery.

When an opponent casts a creature spell, if Opal Archangel is an enchantment, Opal Archangel becomes a 5/5 Angel creature with flying and vigilance.

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

When an opponent casts a creature spell, if Opal Guardian is an enchantment, Opal Guardian becomes a 3/4 Gargoyle creature with flying and protection from red.

Sunburst (This enters the battlefield with a charge counter on it for each color of mana spent to cast it.)

Equipped creature gets +X/+X, where X is the number of charge counters on Opaline Bracers.

Equip (: Attach to target creature you control. Equip only as a sorcery.)

: Add one mana of any color.

X target creatures can't be blocked this turn. Until end of turn, those creatures gain "Whenever this creature deals combat damage to a player, draw a card."

Whenever a nontoken creature you control dies, create a 2/2 black Zombie creature token.

At the beginning of each upkeep, if you control no Snakes, create a 1/1 black Snake creature token with deathtouch.

Flying

When Opportunistic Dragon enters the battlefield, 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.

Whenever a player casts a spell, that player discards a card.

Counter target spell unless its controller pays for each card in your hand.

Living metal (As long as it's your turn, this Vehicle is also a creature.)

Trample

Whenever you attack, bolster 2. The chosen creature gains trample until end of turn. When that creature deals combat damage to a player this turn, convert Optimus Prime.

: Target opponent chooses any number of creatures they control. During that player's next turn, the chosen creatures attack if able, and other creatures can't attack. At the beginning of that turn's end step, destroy each of the chosen creatures that didn't attack this turn. Activate only during your turn.

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.

, : You gain X life.

: All damage that would be dealt to target creature this turn by a source of your choice is dealt to Oracle's Attendants instead.