Chain Spell

 
Prerequisite(s): Any Metamagic Feat (See main index)
 
Benefit: Any spell that specifies a single target and has a range greater than touch, can be chained so as to affect the primary target and then arc to a number os secondary targets equal to your caster level. Each arc affects a target chosen by you but must be within 30' of the primary target. Secondary targets receive half damage from damage dealing spells and are allowed a Reflex save for an additional half damage, even if the spell does not normally allow a reflex save for reduced damage. Spells that do not deal damage have their DC reduced by 4 for all secondary targets. A spell modified with this feat uses a spell slot 3 levels higher than normal.
 
Source: Complete Arcane