Eldritch Conjuror

From publisher blurb: While many who dabble in the arcane become adept at beckoning monsters from the farthest reaches of the planes, none are more skilled at commanding these powers than the eldritch conjuror. This practitioner of the forbidden arts is skilled at summoning the maddening forms of these unspeakable creatures. As a boon from the ancient beings which they drawn the secrets of their magic, an eldritch conjuror is sent a servitor from beyond the stars. This alien creature acts as his servant, gaining power as the eldritch conjuror unlocks of the secrets of madness. As the eldritch conjuror’s mind further erodes from his obsessive study, he eventually becomes a physical vessel for these elder beings. Shedding the weakness of his mortal flesh, he transcends into one of the outsiders from which he draws his powers.