To be able to completely mitigate all spell damage in a rated Player Versus Player scenario followed by rendering yourself untouchable by any physical assaults made against you is asinine. As this class stands, it is worse than Frost DK's and Demon Hunters combined. Demon Hunter's can Nether Walk - but at the cost of a talent slot. Death Knights can can take a stronger Anti Magic Shell - but at the cost of pressure from Inexorable Assault.
This class lacks equivalence. Nerf it.