The monster is called a draugon (please note the u.)
It is essentially an undead dragon.
It looks like a half-living dragon, half-skeleton dragon.
Its breath attacks cause things like disease and curses (what you are afflicted with depends on your level.)
Any other ideas for monsters that could have appeared in Skyrim?
There already is one skeletal dragon in winterhold academy questline.
What about a roughly humanoid creature that can turn itself to smoke/mist form in order to negate all damage, and reverses itself to flesh form in order deal a powerful melee strike which ignores 50% armor with 10% chance to paralyse for 2 seconds? At the moment of changing to material shape the monster would get double vulnerability for damage for 1 second.
Imagine fighting a group of those, that would be something. Also, find a nice name for it since i cannot come up with any.