You can cast spells that arc to other targets in addition to the primary target.
Prerequisite: Any metamagic feat.
Benefit: Any spell that specifies a single target and has a range greater than touch can be chained so as to affect that primary target normally, then arc to a number of secondary targets equal to your caster level (maximum 20). Each arc affects one secondary target chosen by you, all of which must be within 30 feet of the primary target, and none of which can be affected more than once. You can choose to affect fewer secondary targets than the maximum.
If the chained spell deals damage, the secondary targets each take half as much damage as the primary target (rounded down) and can attempt Reflex saving throws for half damage (whether the spell allows the original target a save or not). For spells that don't deal damage, the save DCs against arcing effects are reduced by 4. For example, if a 10th-level wizard normally casts cause fear at DC 14, a chained cause fear could target a goblin chieftain at DC 14 and up to ten of his nearby guards at DC 10.
A chained spell uses up a spell slot three levels higher than the spell's actual level.