Banding, "Bands with Other"
Banding is a keyword ability that modifies the rules for declaring attackers and assigning combat damage. "Bands with other" is a specialized version of the ability. See rule 702.21, "Banding."

Base Power, Base Toughness
Effects that change the base power and/or base toughness of a creature set oneor both of those values to a specific number. See rule 613, "Interaction of Continuous Effects."

Basic
A supertype that’s normally relevant on lands. Any land with this supertype is a basic land. See rule 205.4, "Supertypes."

Basic Land Type
There are five "basic land types": Plains, Island, Swamp, Mountain, and Forest. Each one has a mana ability associated with it. See rule 305, "Lands."

Basic Landcycling
See Typecycling.

Battle Cry
A keyword ability that makes other attacking creatures better in combat. See rule 702.90, "Battle Cry."

Battlefield
A zone. The battlefield is the zone in which permanents exist. It used to be known as the "in-play" zone. See rule 403, "Battlefield."

Becomes
A word used in some trigger events to indicate a change in status or characteristics. See rule 603.2d.

Beginning of Combat Step
Part of the turn. This step is the first step of the combat phase. See rule 507, "Beginning of Combat Step."

Beginning Phase
Part of the turn. This phase is the first phase of the turn. See rule 501, "Beginning Phase."

Bestow
A keyword ability that lets a creature card be cast as an Aura. See rule 702.102, "Bestow."

Block
To send a creature into combat defensively. A creature can block an attacking creature. See rule 509, "Declare Blockers Step."

Block Alone
A creature "blocks alone" if it’s the only creature declared as a blocker during the declare blockers step. A creature "isblocking alone" if it’s blocking but no other creatures are. See rule 506.5.

Blocked Creature
An attacking creature that another creature blocks or that an effect causes to become blocked. It remains a blocked creature until it’s removed from combat, an effect says that it becomes unblocked, or the combat phase ends, whichever comes first. See rule 509, "Declare Blockers Step."

Blocking Creature
A creature that has either been declared as part of a legal block during the combat phase (once all costs to block, if any, have been paid), or a creature that has been put onto the battlefield blocking. It remains a blocking creature until it’s removed from combat or the combat phase ends, whichever comes first. See rule 509, "Declare Blockers Step."

Bloodthirst
A keyword ability that can have a creature enter the battlefield with +1/+1 counters on it. See rule 702.53, "Bloodthirst."

Bolster
A keyword action that puts +1/+1 counters on the weakest creature a player controls. See rule 701.31, "Bolster."

Booster Pack
A group of unopened Magic cards from a particular expansion. Booster packs are used in Limited formats. See rule 100.2b.

Bury (Obsolete)
A term that meant "put [a permanent] into its owner’s graveyard." In general, cards that were printed with the term "bury" have received errata in the Oracle card reference to read, "Destroy [a permanent]. It can’t be regenerated," or "Sacrifice [a permanent]."

Bushido
A keyword ability that can make a creature better in combat. See rule 702.44, "Bushido."

Buyback
A keyword ability of instants and sorceries that can let the spell return to its owner’s hand as it resolves. See rule 702.26, "Buyback."