So i have worked out accidently that you can force the draugr out of the tombs including the dragon priests regardless of the fact they are LOCKED into their tomb and require you to go and get keys to unluck the coffin.

A rune at the base of their coffin instantly goes off and they come out.

While this is obviously a glitch it is something that can be exploited at various points to make mob battles a hell of a lot easier because it only wakes up that one draugr each time as the rest are not activated - they are still secretly waiting for you to lift that key or book before surprise attack