Bigby's interposing hand creates a Large magic hand that
appears between the character and one opponent. This floating,
disembodied hand then moves to remain between the two, regardless
of where the character moves or how the opponent tries to get
around it, providing nine-tenths cover (+10 AC) for the character
against that opponent. Nothing can fool the hand-it sticks with
the selected opponent in spite of darkness, invisibility,
polymorphing, or any other attempt to hide or disguise himself.
The hand does not pursue an opponent, however.
A Bigby's hand is 10 feet long and about that wide with its
fingers outstretched. It has as many hit points as the character
when undamaged, and its AC is 20 (-1 size, +11 natural). It takes
damage as a normal creature, but most magical effects that don't
cause damage do not affect it. The hand cannot push through a
wall of force or enter an antimagic field. It suffers the full
effects of a prismatic wall or prismatic sphere. The hand makes
saving throws as its caster. Disintegrate or a successful dispel
magic destroys the hand.
Any creature weighing less than 2,000 pounds trying to push
past the hand is slowed to half its normal speed. If the opponent
weighs more than 2,000 pounds, the hand cannot reduce its speed
but still affects the opponent's attacks.
By concentrating (as a standard action), the character can
designate a new opponent for the hand.