These "sith magics" as near as i can tell are basically twisted evil force use of the darkside.
I do not know of any such magic, but i will guiv u a hypothectical
A sith uses the force, and many different potions to allow him to live forever. If his body is destroyed, it would still remain in concealment, until this sith had enough power to rise again.
Problably not the best example around.
For a good explanatioon on Sith Magaics ask Nur Ab Sal
In the movies, we never really see Vaders full potetial. In KOTOR, we enver really see anything of Darth Revan.
I still beleive that they r evenly matched.