The Warmage can be found in its entirety in Complete Arcane. The warmage follows the class progression found within with these exceptions.
The Warmage’s advanced learning follows the example given for the Sorcerer.
The Warmage becomes a sorcerer variant, meaning it may not multi-class with any other sorcerer variant found in this document.
The Warmage converts to this spellcasting system, including the use of Intelligence the primary relevant ability score and Charisma as the secondary relevant ability score. 

Spell List: The warmage's spell list (the list a warmage chooses his Spells Known from) consists of all cleric, druid and sorcerer/wizard spells of the evocation school, plus the following spells:
Level 0: acid splash, disrupt undead
Level 1: accuracy, chill touch, fist of stone, hail of stone, orb of acid (lesser), orb of cold (lesser), orb of electricity (lesser), orb of fire (lesser), orb of sound (lesser), true strike
Level 2: blades of fire, fire trap, ice knife, melf's acid arrow, pyrotechnics, whirling blade
Level 3: flame arrow, poison, ring of blades, sleet storm, stinking cloud
Level 4: blast of flame, contagion, evard's black tentacles, orb of acid, orb of cold, orb of electricity, orb of fire, orb of force, orb of sound, phantasmal killer
Level 5: arc of lightning, cloudkill
Level 6: acid fog, circle of death, disintegrate, fighter's transformation
Level 7: finger of death, waves of exhaustion
Level 8: horrid wilting, incendiary cloud, prismatic wall, scintillating pattern
Level 9: elemental swarm, prismatic sphere, wail of the banshee, weird