Benefit

You can twin a spell. Casting a spell altered by this feat causes the spell to take effect twice on the area or target, as if you were simultaneously casting the same spell two times on the same location or target. Any variables in the spell (such as duration, number of targets, and so on) are the same for both of the resulting spells. The target experiences all the effects of both spells individually and receives a saving throw (if applicable) for each. In some cases, such as a twinned Charm Person, failing both saving throws results in redundant effects (although, in this example, any ally of the target would have to succeed on two dispel attempts to free the target from the charm effect).

A twinned spell uses up a spell slot four levels higher than the spell’s actual level.