I was thinking that in certain worlds where the Blood War doesn't exist like in Eberron or in the world where Drakkenheim takes place you could potentially face a united force of Demons and Devils which would be very interesting. In the case of Eberron the Fiends could come from Khyber alongside Aberrations while in Drakkenheim's World a Cult might open a portal to Hell since there was no distinction mentioned.
I was thinking that in certain worlds where the Blood War doesn't exist like in Eberron or in the world where Drakkenheim takes place you could potentially face a united force of Demons and Devils which would be very interesting. In the case of Eberron the Fiends could come from Khyber alongside Aberrations while in Drakkenheim's World a Cult might open a portal to Hell since there was no distinction mentioned.