Heretic Spellblade
K.D. Robertson
Before the demons invaded, Nathan had everything: power, magical talent, wealth, and a fortress of loyal soldiers. Given a second chance by a demonic general, he is sent back in time to before the end of the world — stripped of everything he earned but armed with years of knowledge. To rewrite history and stop the end of Doumahr, Nathan must re-walk the path of a heretic: mastering forbidden spellcraft, taming demonic Messengers, and outmaneuvering prophets, inquisitions, and empires. (Paraphrased from verified Goodreads volume descriptions.)
Progression: LitRPG regression progression (Goodreads genre tag: Litrpg, verified on book 1 page). Nathan retains knowledge from his first life and re-advances further and faster along heretic spellcraft: forbidden magic, demonic Messenger bonds, ancient spells, and escalating world-scale threats across 8 volumes. Explicit advancement path referenced in volume blurbs ('step further along the path of a heretic', 'utilize every trick and spell he's learned').
Goodreads
