Demon Devourer

The descendant of a once great wizarding family, Elric Mervinger is unable to perform magic due to a rare medical condition. While attempting to cure his disease, he stumbles upon the demon Mephistopheles, who tries to possess Elric to free himself from a dragon's trap. But when Elric ends up absorbing Mephisto instead, the two become bound together. With Mephisto by his side, will this new power allow Elric to restore his family to its former glory? Or will he just end up being devoured?

Elric Melvinger. The sole heir of the prestigious magic family. Though he possessed innate talent, he had too much talent, and as such, could not learn magic. However, he then received a blessing left by his ancestors! [Eat demons.] [Swallow demons.] [Drink demons.] [Continue to keep accumulating demons within yourself, and achieve new magic!] Reach high. Reach a height so high that no one will ever reach me.