If you look at descendum, travelling to (your) hell could be a pretty pointless power but if you look at it in another way, I think it's a power to travel around Hell and find spirits and souls. Like how Queenie went to Hell to talk to Papa Legba.
And everyone you see in Hell is actually dead too, forever living in the scene. Like the man in Queenie's Hell who "forever smells the delicious chicken but unable to take a bite" or Marie Laveau is forever stuck in LaLaurie's Hell. I think Descedum allows the witch to travel to Hell and find these souls