The Abathar gives it in the Gulshan graveyard, he sends us to look for Asmodeus, but I can't find him, does anyone know where he is hidden? Thanks

north from that npc, youll find a hole that leads to a vampire cave.
there you may find coffins arround the map, right click on the coffin and you get a chance to spanw asmodeus.
stay sharp, he hits hard.

if you get unlucky, dont worry, the coffin reset within some minutes.