You have no maximum hand size.

Sonic Booster — Whenever Nyssa of Traken attacks, sacrifice any number of artifacts. When you sacrifice one or more artifacts this way, tap up to that many target creatures and draw that many cards.

Doctor's companion (You can have two commanders if the other is the Doctor.)

Enchant creature

Enchanted creature gets +2/+2 as long as it's an enchantment. Otherwise, it gets -2/-2.

Reach

At the beginning of your upkeep, mill two cards. (Put the top two cards of your library into your graveyard.)

, Exile Nyx Weaver: Return target card from your graveyard to your hand.

Trample

If you tap a permanent for mana, it produces three times as much of that mana instead.

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.)

Reach, trample

Nyxborn Hydra enters with X +1/+1 counters on it.

Enchanted creature gets +1/+1 for each +1/+1 counter on Nyxborn Hydra and has reach and trample.

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.)

Enchanted creature gets +1/+1.

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.)

Enchanted creature gets +1/+2.

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.)

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

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

At the beginning of your upkeep, you gain 1 life.

Put two +1/+1 counters on target creature. (Then exile this card. You may cast the creature later from exile.)

Whenever you crank Oaken Power Suit, target creature gets +X/+X until end of turn, where X is the greatest power among creatures you control.

Enchant creature

Enchanted creature gets +3/+3.

This spell costs less to cast if an opponent controls a green permanent.

Deathtouch

Whenever Oakhame Adversary deals combat damage to a player, draw a card.

Constellation — Whenever Oakheart Dryads or another enchantment you control enters, target creature gets +1/+1 until end of turn.

You may cast Oakshade Stalker as though it had flash if you pay more to cast it.

Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

: Prevent the next 1 damage that would be dealt to target creature this turn.

: Add one mana of any color.

, Exert Oasis Ritualist: Add two mana of any one color. (An exerted creature won't untap during your next untap step.)

When Oath of Chandra enters, it deals 3 damage to target creature an opponent controls.

At the beginning of each end step, if a planeswalker entered the battlefield under your control this turn, Oath of Chandra deals 2 damage to each opponent.

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

I — Create two 1/1 white Human Soldier creature tokens.

II — Create two 2/2 red Human Knight creature tokens with trample and haste.

III — Put an indestructible counter on up to one target Human. You become the monarch.

When Oath of Gideon enters, create two 1/1 white Kor Ally creature tokens.

Each planeswalker you control enters with an additional loyalty counter on it.

When Oath of Kaya enters, it deals 3 damage to any target and you gain 3 life.

Whenever an opponent attacks a planeswalker you control with one or more creatures, Oath of Kaya deals 2 damage to that player and you gain 2 life.

When Oath of Liliana enters, each opponent sacrifices a creature.

At the beginning of each end step, if a planeswalker entered the battlefield under your control this turn, create a 2/2 black Zombie creature token.

At the beginning of each player's upkeep, that player chooses target player who has more life than they do and is their opponent. The first player may have Oath of Mages deal 1 damage to the second player.

At the beginning of each player's upkeep, that player chooses target player who has more cards in hand than they do and is their opponent. The first player may discard their hand and draw three cards.

Whenever Oath of the Ancient Wood or another enchantment you control enters, you may put a +1/+1 counter on target creature.

Equipped creature gets +3/+1.

Whenever equipped creature dies, return that card to the battlefield under your control if it's a Samurai card.

When Oathkeeper, Takeno's Daisho is put into a graveyard from the battlefield, exile equipped creature.

Equip

Oathsworn Knight enters with four +1/+1 counters on it.

Oathsworn Knight attacks each combat if able.

If damage would be dealt to Oathsworn Knight while it has a +1/+1 counter on it, prevent that damage and remove a +1/+1 counter from it.

+2: Each opponent loses 1 life. You gain life equal to the life lost this way.

−2: Create a 5/5 black Demon creature token with flying. You lose 2 life.

−8: You get an emblem with ", Sacrifice a creature: You gain X life and draw X cards, where X is the sacrificed creature's power."

Ob Nixilis of the Black Oath can be your commander.

Flying, trample

Whenever one or more opponents each lose exactly 1 life, put a +1/+1 counter on Ob Nixilis, Captive Kingpin. Exile the top card of your library. Until your next end step, you may play that card.

Landfall — Whenever a land you control enters, you may have target player lose 3 life. If you do, put three +1/+1 counters on Ob Nixilis, the Fallen.

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.

This spell can't be countered.

Destroy all artifacts, creatures, and lands. They can't be regenerated.

Aftermath (Cast this spell only from your graveyard. Then exile it.)

Target opponent discards two cards.

When Oblivion Ring enters, exile another target nonland permanent.

When Oblivion Ring leaves the battlefield, return the exiled card to the battlefield under its owner's control.

, : 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: Untap target land.

: Add .

: Return Oboro, Palace in the Clouds to its owner's hand.

Whenever you cast a spell, if its mana value is equal to 1 plus the number of soul counters on Obscura Ascendancy, put a soul counter on Obscura Ascendancy, then create a 2/2 white Spirit creature token with flying.

As long as there are five or more soul counters on Obscura Ascendancy, Spirits you control get +3/+3.

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.)

When Obscura Storefront enters, sacrifice it. When you do, search your library for a basic Plains, Island, or Swamp card, put it onto the battlefield tapped, then shuffle and you gain 1 life.