A creature's reach is the distance at which it can strike targets with its natural weapons
without needing to adjust its position on the grid. A creature using its natural weapons
threatens all squares within its reach. When measuring diagonally, every second square counts as two squares. Table: Creature Sizes provides the typical reach for creatures
of any given size
. The GM may adjust the values in the table by -5 feet or +5 feet for creatures
that have less than normal or greater than normal reach. Unlike the wielder of a reach weapon, a creature with greater than normal reach (more than 5 feet) can still strike creatures
next to it. A creature with greater than normal reach usually gets an attack of opportunity
against a character if the character approaches it, because the character enters a square it threatens before he or she can attack it. (This does not apply if the character takes a 5-foot step.) Large or larger creatures
with reach weapons can strike targets out to double their reach but can't strike at targets within their normal reach or less.
A creature with a 0-foot reach must move into the fighting space of its target to attack it, provoking an attack of opportunity
from the target as the creature enters the target's fighting space and threatened area. Also, creatures
with 0-foot reach do not threaten the squares around them.