Widen Spell( Player's Handbook v.3.5, p. 102)
You can increase the area of your spells.
You can alter a burst, emanation, line, or spread shaped spell to increase its area. Any numeric measurements of the spell's area increase by 100%. For example, a fireball spell (which normally produces a 20-foot-radius spread) that is widened now fills a 40-footradius spread. A widened spell uses up a spell slot three levels higher than the spell's actual level. Spells that do not have an area of one of these four sorts are not affected by this feat.