Berserk Possed Horse (Baka ABC, Hentai Creature Addon)

Possed Horse From Berserk

Creature based Horse 

theres only One spawned

near at the Hall of Death of Falkreath

also include

Hentai Creature(https://www.loverslab.com/files/file/5464-more-nasty-critters-special-edition/) addon mod  

you can get this summon spell book using AIM SE(additemmenu) or additem console cheat