Type of Feat: Metamagic
Prerequisite: Ability to cast 3rd-level spells.
Specifics: Maximized spells apply all variable numeric effects - including damage, number of targets, and so on - at their maximum values.
Use: A maximized spell occupies a spell slot three levels higher than normal. Saving throws and opposed rolls, such as those made when Dispel Magic is cast, are not affected.
A comparison of Empower Vs Maximize that goes over the benefits of each, and to help you decide what to take.
For a list of all spells which can be enhanced by this feat, see: Category:Spells that can be Maximized.