D&D 5E Looking find a decent place for random demon stat blocks

[Christopher Bixby]

So on of my table rules is one that I thought would be interesting to implement while doing our sessions and that is when three players each roll a 6 while doing initiative rolls a random demon will appear and the party has to defeat it in some way. Now the only thing is is that I cannot find any that would be a good choice for the ancient Norse worlds. If anyone could direct me to where I could find something on the subject it would be greatly appreciated.

 

[Quickleaf]

Is there a realm of demons in Norse myth? I always thought there were 9 realms: the worlds of the gods (Asgarth), of the Vanir deities (Vanaheim), of the elves (Alfheim), of men (Mithgarth/Midgard), of the giants - which seem more like frost, stone, or hill giants (Jotunheim), of fire (Muspellsheim), of the dark elves (Svartalfheim), of the dead (Niflheim), and of the dwarfs (Nithavellir).

Are you interpreting the fire giants of Muspellsheim as demons instead? Then anything with a fire theme could work. The immolith for example?