» Sat Mar 09, 2013 6:48 am
Necromancing draws spiritual energy from the Dreamsleeve. It doesn't need to be the original soul.
With dragons, their souls are left inside their bodies when killed by a non-dragonborn. The skeletal dragon was probably just reanimated bones, not necessarily an actual dragon anymore.
Once you take a dragon's soul, the dragon's not getting back up. A shout that temporally gives the soul back could be interesting.