This spell creates an electrical discharge that begins as a
single stroke commencing from the character's fingertips. Unlike
lightning bolt, chain lightning strikes one object or creature
initially, then arcs to other targets.
The bolt deals 1d6 points of electricity damage per caster
level (maximum 20d6) on the primary target. After the bolt
strikes, lightning can arc to as many secondary targets as the
character has levels. The secondary bolts each strike one target
and deal half as many dice of damage as the primary (rounded
down). All subjects can attempt Reflex saving throws for half
damage. The character chooses secondary targets as the character
likes, but they must all be within 30 feet of the primary target,
and no target can be struck more than once. The character can
choose to affect fewer secondary targets than the maximum (to
avoid allies in the area, for example).