Off the top of my head I came up with a class that maybe, just maybe, makes the evocation school of spells more useful.
Yes, this is generic. It is intended to be.
Level BAB Fort Ref Will Special Spells 1st +0 +0 +0 +2 Intensified Spells, Chosen Element - 2nd +1 +0 +0 +3 Energy Admixture, Elemental Affinity (Chosen Element) +1 +1 level of existing spellcasting class 3rd +1 +1 +1 +3 Deep Impact +1 level of existing spellcasting class 4th +2 +1 +1 +4 Elemental Affinity (Chosen Element) +2 +1 level of existing spellcasting class 5th +2 +1 +1 +4 Mastery Of The Element +1 level of existing spellcasting class
Skill Points: 2+Int
Class Skills: As Wizard
Skills: Knowledge (Arcana) 8, Knowledge (The Planes) 4
Spellcasting: Ability to cast 2nd level arcane spells.
Feats: Energy Substitution(chosen element)
Chosen Element(Ex): Pick one element for which you have the Energy Substitution feat. All the abilities of this class will work only with spells that posses this energy descriptor.
Furthermore, you can spontaneously apply the Energy Substitution metamagic feat of your chosen element to any applicable evocation spell you cast without increasing its casting time.
Intensified Spells(Ex): At 1st level, you begin to understand how to utilize your chosen element with greater power. All the maximum damage die limits of the spells of your chosen element are increased by your level in this class.
E.g. Fireball cast by a Wizard6/Elemental Evoker5 would deal 12d6 fire damage and cap out at 15d6.
Elemental Affinity(Su): At 2nd level you gain +1 caster level for all spells of your chosen energy descriptor. This becomes +2 at 4th level.
Energy Admixture: At 2nd level you gain Energy Admixture(your chosen element) as a bonus feat.
Deep Impact(Ex): Beginning at 3rd level, spells of your chosen element ignore half the target's energy resistance and still deal 50% damage to the targets normally immune.
Mastery Of The Element(Ex):At 5th level you learn how to cast your spells more effectively. While applying metamagic feats to the evocation spells of your chosen element, the spell level cost is reduced by one, to a minimum of +0.
Furthermore, while casting an Evocation spell of your chosen element that allows a Reflex Saving Throw, as a move action you may change its Saving Throw to Fortitude instead.
EDIT1: Changed requirements to explicitly require ARCANE magic (Which was intended from the beginning), added a spellcasting level tax, made it work only with evocations.
EDIT2: Changed the wording of the 5th level ability, changed the levels at which you gain Elemental Affinity and Intensified Spells.
EDIT3: Made some changes meant to be there from the very beginning, namely the class abilities working only with one, chosen element.
EDIT4: Changed some wording.