Flying, trample

Whenever an opponent searches their library, that player sacrifices a creature and loses 10 life.

Whenever another creature dies, put a +1/+1 counter on Ob Nixilis, Unshackled.

: The player whose turn it is may end the turn. (Exile all spells and abilities from the stack. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

, : You gain 5 life.

, : Draw a card, then discard a card.

, : Target creature gets -2/-2 until end of turn.

, : Obelisk of Alara deals 3 damage to target player or planeswalker.

, : Target creature gets +4/+4 until end of turn.

: Add , , or .

: Add , , or .

, : Return target permanent you both own and control to your hand.

Reach

Whenever Obelisk Spider deals combat damage to a creature, put a -1/-1 counter on that creature.

Whenever you put one or more -1/-1 counters on a creature, each opponent loses 1 life and you gain 1 life.

Obliterating Bolt deals 4 damage to target creature or planeswalker. If that creature or planeswalker would die this turn, exile it instead.

, : Put a fate counter on target permanent.

, , Sacrifice Oblivion Stone: Destroy each nonland permanent without a fate counter on it, then remove all fate counters from all permanents.

Target creature you control gains indestructible until end of turn. Draw a card if that creature has a +1/+1 counter on it. (Damage and effects that say "destroy" don't destroy the creature.)

Flying

, Return a land you control to its owner's hand: Target creature gets -X/-0 until end of turn, where X is the number of cards in your hand.

Companion — Your starting deck contains only cards with odd mana values and land cards. (If this card is your chosen companion, you may put it into your hand from outside the game for as a sorcery.)

If a source you control with an odd mana value would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Choose three. You may choose the same mode more than once.

• Until end of turn, target creature loses all abilities and has base power and toughness 1/1.

• Target creature connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on that creature.)

• Target player returns a creature card from their graveyard to their hand.

Flash

Lifelink

When Obscura Interceptor enters, it connives. When it connives this way, return up to one target spell to its owner's hand. (To have a creature connive, draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on that creature.)

Face-down creature spells you cast cost less to cast.

: Turn Obscuring Aether face down. (It becomes a 2/2 creature.)

Bestow (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)

Vigilance

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

Flying, ward

Whenever Obsessive Collector deals combat damage to a player, seek a card with mana value equal to the number of cards in your hand.

When Obsessive Skinner enters, put a +1/+1 counter on target creature.

Delirium — At the beginning of each opponent's upkeep, if there are four or more card types among cards in your graveyard, put a +1/+1 counter on target creature.

Equipped creature gets +2/+1 and has haste.

Whenever a Warrior creature enters, you may attach Obsidian Battle-Axe to it.

Equip

Obsidian Obelisk enters tapped.

: Add .

: Add one mana of any color. Spend this mana only to cast a multicolored spell.

If you would draw a card, you may skip that draw instead.

At the beginning of combat on your turn, up to one target land you control becomes an X/X Elemental creature with trample and haste until end of turn, where X is Obuun's power. It's still a land.

Landfall — Whenever a land you control enters, put a +1/+1 counter on target creature.

Flying

Return target permanent card from your graveyard to the battlefield.

Flying

When Oceanus Dragon enters, tap target creature an opponent controls. Goad it. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

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.

Gift an Octopus (You may promise an opponent a gift as you cast this spell. If you do, when it enters, they create an 8/8 blue Octopus creature token.)

At the beginning of each end step, create a token that's a copy of target creature token that entered the battlefield this turn.

Flying

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

Flip a coin. If it comes up heads, counter target instant or sorcery spell. If it comes up tails, copy that spell and you may choose new targets for the copy.

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.

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

Draw two cards.

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.