Umbral Spell
( Drow of the Underdark, p. 52)[General, Metamagic]
You add the darkness descriptor to a spell you cast.
Prerequisite
Benefit
You can alter a burst-, emanation-, or spread-shaped spell so that it gains the darkness descriptor. The altered spell automatically dispels any spells with the light descriptor of the spell's level or lower whose effects overlap or are within the altered spell's area.
For example, an umbral lightning bolt would dispel any ongoing light spell of 3rd level or lower in the area of the line. An umbral spell uses up a spell slot one level higher than the spell's actual level.