It’s a TRAP! Unless your campaign regularly features large set battles with hordes of extremely weak foes, there will be very few times that a larger fireball will be better than a more intense one. In fact, this feat is best used with sabotage spells like Black Tentacles, Solid Fog, and Acid Fog, rather than damaging spells like fireball. Even then, however, it’s not much use. Steer clear of this feat unless your campaign regularly features massive battles with numerous combatants. I direct you to the Sudden Widen feat if you feel that you need extra area effect on a regular basis.
