Each non-Vampire creature gets -X/-X until end of turn, where X is the number of Vampires you control.

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.

Flash

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

, Sacrifice Omen of the Dead: Scry 2.

Flash

When Omen of the Hunt enters the battlefield, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

, Sacrifice Omen of the Hunt: Scry 2.

Flash

When Omen of the Sun enters the battlefield, create two 1/1 white Human Soldier creature tokens and you gain 2 life.

, Sacrifice Omen of the Sun: Scry 2.

Omenport Vigilante has double strike as long as you've committed a crime this turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

When Ominous Roost enters the battlefield and whenever you cast a spell from your graveyard, create a 1/1 blue Bird creature token with flying and "This creature can block only creatures with flying."

If you would lose unspent mana, that mana becomes black instead.

At the beginning of your precombat main phase, look at the top card of your library. You may reveal that card if it has three or more colored mana symbols in its mana cost. If you do, add three mana in any combination of its colors and put it into your hand. If you don't reveal it, put it into your hand.

You don't lose unspent green mana as steps and phases end.

Omnath, Locus of Mana gets +1/+1 for each unspent green mana you have.

When Omnath, Locus of the Roil enters the battlefield, it deals damage to any target equal to the number of Elementals you control.

Landfall — Whenever a land enters the battlefield under your control, put a +1/+1 counter on target Elemental you control. If you control eight or more lands, draw a card.

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.

O-Naginata can be attached only to a creature with power 3 or greater.

Equipped creature gets +3/+0 and has trample.

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

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.

If this spell is the first spell you've cast this game, you may cast it without paying its mana cost.

Look at the top five cards of your library. You may reveal a creature or land card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

First strike

Landfall — Whenever a land enters the battlefield under your control, Ondu Greathorn gets +2/+2 until end of turn.

Whenever an enchantment enters the battlefield under your control, you may create a token that's a copy of it. Do this only once each turn.

At the beginning of each upkeep, if a player cast two or more spells last turn, transform One of the Pack.

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

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.

Flash

Enchant creature you control

Whenever enchanted creature or another modified creature you control dies, create X 1/1 colorless Spirit creature tokens, where X is that creature's power. (Equipment, Auras you control, and counters are modifications.)

You may look at the top card of your library any time.

You may play lands and cast spells from the top of your library.

Once during each of your turns, you may cast a spell from your hand or the top of your library without paying its mana cost.

Enchant creature

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

Whenever one or more artifacts you control leave the battlefield during your turn, create a 1/1 colorless Construct artifact creature token. This ability triggers only once each turn.

, Sacrifice an artifact: Oni-Cult Anvil deals 1 damage to each opponent. You gain 1 life.

When Onulet dies, you gain 2 life.

: Target player loses 1 life.

Flying

: Choose a color. Target opponent exiles the top X cards of their library. For each card of the chosen color exiled this way, create a 1/1 blue and black Faerie Rogue creature token with flying.

Whenever an opponent casts a creature spell, if Opal Acrolith is an enchantment, Opal Acrolith becomes a 2/4 Soldier creature.

: Opal Acrolith becomes an enchantment.

When Opal Lake Gatekeepers enters the battlefield, if you control two or more Gates, you may draw a card.

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."

Search your library for a basic land card or Gate card, reveal it, put it into your hand, then shuffle.

Choose one —

• Add two mana of any one color and two mana of any other color. Spend this mana only to cast creature or enchantment spells.

• Creatures you control get +1/+0 until end of turn.

X can't be greater than the number of players in the game.

Reveal cards from the top of your library until you reveal X land cards. Put those land cards onto the battlefield tapped and the rest on the bottom of your library in a random order.

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.

Tap an untapped creature you control: Tap target artifact, creature, or land.

Scry 1.

Draw a card.

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.

Opulent Palace enters the battlefield tapped.

: Add , , or .

, : 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.

, : Exile the top card of your library. Until end of turn, you may play that card. Put a brick counter on Oracle's Vault.

: Exile the top card of your library. Until end of turn, you may play that card without paying its mana cost. Activate only if there are three or more brick counters on Oracle's Vault.

Whenever Oran-Rief Survivalist or another Ally enters the battlefield under your control, you may put a +1/+1 counter on Oran-Rief Survivalist.

As an additional cost to cast this spell, you may reveal a Dragon card from your hand.

Defender, flying

When Orator of Ojutai enters the battlefield, if you revealed a Dragon card or controlled a Dragon as you cast this spell, draw a card.

Whenever another creature enters the battlefield under your control, target creature an opponent controls gets -1/-1 until end of turn.

Orchard Spirit can't be blocked except by creatures with flying or reach.

: Orcish Artillery deals 2 damage to any target and 3 damage to you.

Flash

When Orcish Bowmasters enters the battlefield and whenever an opponent draws a card except the first one they draw in each of their draw steps, Orcish Bowmasters deals 1 damage to any target. Then amass Orcs 1.

Orcish Conscripts can't attack unless at least two other creatures attack.

Orcish Conscripts can't block unless at least two other creatures block.