Description: When cast outside, the spell has an instant duration. All enemies within the area of effect take 1d6 points of electrical damage per caster level, to a maximum of 10d6.
When cast inside, the spell has a duration of 1 round / level. Each round a random enemy in the area of effect is struck for 1d6 points of electrical damage per caster level, to a maximum of 10d6. There is a chance the lightning arcs into a wall, floor or ceiling instead. This chance is 20% if 8 enemies are in the area of effect and increases to 67% if only one enemy remains.
A successful reflex save halves the damage taken.