Divine Presence

The caster has to submerge their right hand in the demon's blood and their left in the hydra's bile.  After both hands are submerged, the caster has to slit the sacrifice's throat.  The caster recites a forbidden chant in abyssal for the next 10 hours.  The caster can stop the casting of the spell at any time however if the spell ends they have to restart the casting of it.  If the spell is completed, a lesser god of the caster's choice appears before them.  The god is locked on the caster's plane of existence until the caster dies or frees them.  The god has free will and can do anything within their power except kill the caster.  An arcane focus can't replace any of this spell's components.  This spell can only be cast while in possession of The Elder Scroll.