: The description of the spiked chain states that it is a
reach weapon that can be used against adjacent foes. What
if a Large creature wields a Large spiked chain? Can it
attack the squares that are 10 feet away? What are the
adjacent foes of a Large or larger creature?
A: As with the vast majority of examples in the Player’s
Handbook, the spiked chain description assumes that the
wielder is a Small or Medium creature wielding a spiked chain
appropriate to her size. What the description really means is
that a character wielding a spiked chain can attack creatures
that are within her natural reach (in addition to those at the
normal range of a reach weapon). For a Medium or Small
creature, that means creatures that are 5 feet away (i.e.,
“adjacent”).
A Large creature wielding a spiked chain (or similar reach
weapon that also allowed attacks against adjacent creatures)
could attack creatures within her natural reach (that is, who are
either 5 or 10 feet away), in addition to those at the normal
range of a Large reach weapon (15 or 20 feet away).
A Huge creature wielding a spiked chain could attack
creatures 5, 10, 15, 20, 25, or 30 feet away. A Gargantuan
creature wielding a spiked chain could attack creatures 5, 10,
15, 20, 25, 30, 35, or 40 feet away, and a Colossal creature
wielding a spiked chain could attack creatures anywhere from 5
to 60 feet away