The light of burning shadows - Chris Evans

Konowa Swift Dragon was once commander of the Iron Elves, the legendary Elven regiment of the human army of the Calahrian Empire. Now recalled from exile and disgrace, he is second-in-command of the reconstituted regiment -- a motley band of misfits who are elves in name alone. Konowa's destiny is to stand against the looming threat of the Shadow Monarch, whose destructive ambitions have called down an alien power from the stars and riven the land with all manner of ancient evils. The same Shadow Monarch whose tainted mark he bears...
His quest leads Konowa deep into the desert wastes: the burning lands to which the original Iron Elves were banished. There he and his current companions must face trials beyond their imagining, to learn how to defeat the Shadow Monarch for all time.