Betroth the Beast

Create a Royal Role token attached to target creature you control. (Enchanted creature gets +1/+1 and has ward {1}.)

Besotted Knight

Besotted Knight // Betroth the Beast

Bespoke Battlegarb

Equipped creature gets +2/+0.
Celebration — At the beginning of combat on your turn, if two or more nonland permanents entered the battlefield under your control this turn, attach Bespoke Battlegarb to up to one target creature you control.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Barrier of Bones

Defender
When Barrier of Bones enters, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Bladetusk Boar

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Bridled Bighorn

Vigilance
Whenever Bridled Bighorn attacks while saddled, create a 1/1 white Sheep creature token.
Saddle 2 (Tap any number of other creatures you control with total power 2 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Balduvian Bears

Generous Soul

Flying, vigilance
If Generous Soul would be put into a graveyard from anywhere, exile it instead.

Beloved Beggar

Disturb {4}{W}{W} (You may cast this card from your graveyard transformed for its disturb cost.)

Beloved Beggar // Generous Soul

Burn Bright

Creatures you control get +2/+0 until end of turn.

Blacksnag Buzzard

Flying
Blacksnag Buzzard enters with a +1/+1 counter on it if a creature died this turn.
Plot {1}{B} (You may pay {1}{B} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Burrog Befuddler

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, target creature an opponent controls gets -1/-0 until end of turn.

Battle-Rage Blessing

Target creature gains deathtouch and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Backstreet Bruiser

Defender
As long as there are two or more counters among creatures you control, Backstreet Bruiser can attack as though it didn't have defender.

Dire-Strain Demolisher

Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Burly Breaker

Ward {1} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Burly Breaker // Dire-Strain Demolisher

Byway Barterer

Menace
Whenever you expend 4, you may discard your hand. If you do, draw two cards. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

Blade Banish

Exile target creature with power 4 or greater.

Blademane Baku

Whenever you cast a Spirit or Arcane spell, you may put a ki counter on Blademane Baku.
{1}, Remove X ki counters from Blademane Baku: For each counter removed, Blademane Baku gets +2/+0 until end of turn.

Bladed Battle-Fan

Flash
When Bladed Battle-Fan enters, attach it to target creature you control. That creature gains indestructible until end of turn.
Equipped creature gets +1/+0.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Bloodhunter Bat

Flying
When Bloodhunter Bat enters, target player loses 2 life and you gain 2 life.

Blooming Blast

Gift a Treasure (You may promise an opponent a gift as you cast this spell. If you do, they create a Treasure token before its other effects. It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Blooming Blast deals 2 damage to target creature. If the gift was promised, Blooming Blast also deals 3 damage to that creature's controller.

Blood Burglar

During your turn, Blood Burglar has lifelink.(Damage dealt by this creature also causes you to gain that much life.)

Forest

Benthic Biomancer

{1}{U}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on Benthic Biomancer, draw a card, then discard a card.

Brazen Blademaster

Whenever Brazen Blademaster attacks while you control two or more artifacts, it gets +2/+1 until end of turn.

Blighted Burgeoning

Enchant land
When Blighted Burgeoning enters, incubate 2. (Create an Incubator token with two +1/+1 counters on it and "{2}: Transform this artifact." It transforms into a 0/0 Phyrexian artifact creature.)
Whenever enchanted land is tapped for mana, its controller adds an additional one mana of any color.

Bloody Betrayal

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. Create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Bronzeplate Boar

Trample
Equipped creature gets +3/+2 and has trample.
Reconfigure {5} ({5}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Balduvian Barbarians

Plains

Boggart Brute

Menace (This creature can't be blocked except by two or more creatures.)

Baleful Beholder

When Baleful Beholder enters, choose one —
• Antimagic Cone — Each opponent sacrifices an enchantment of their choice.
• Fear Ray — Creatures you control gain menace until end of turn. (A creature with menace can't be blocked except by two or more creatures.)

Swamp

Bark-Knuckle Boxer

Whenever you expend 4, Bark-Knuckle Boxer gains indestructible until end of turn. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

Barrier Breach

Exile up to three target enchantments.
Cycling {2} ({2}, Discard this card: Draw a card.)

Beacon Bolt

Beacon Bolt deals damage to target creature equal to the total number of instant and sorcery cards you own in exile and in your graveyard.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Island

Mountain

Bouncer's Beatdown

This spell costs {2} less to cast if it targets a black permanent.
Bouncer's Beatdown deals X damage to target creature or planeswalker, where X is the greatest power among creatures you control. If that creature or planeswalker would die this turn, exile it instead.

Bristling Boar

Bristling Boar can't be blocked by more than one creature.

Breakneck Berserker

Blizzard Brawl

Choose target creature you control and target creature you don't control. If you control three or more snow permanents, the creature you control gets +1/+0 and gains indestructible until end of turn. Then those creatures fight each other. (Each deals damage equal to its power to the other.)

Boom Box

{6}, {T}, Sacrifice Boom Box: Destroy up to one target artifact, up to one target creature, and up to one target land.

Bartizan Bats

Flying (This creature can't be blocked except by creatures with flying or reach.)

Bristling Backwoods

Bristling Backwoods enters tapped.
When Bristling Backwoods enters, it deals 1 damage to target opponent.
{T}: Add {R} or {G}.