Living dead, as it currently is, is fine. What would be nice, though, is to give the DRK a buff for surviving it. Giving a "reward" to the party whose healers were able to keep the DRK alive through the storm.

Something like this:
Return to the Living: Activates when Walking Dead is successfully removed. Decreases damage taken by 10% while simultaneously increasing damage dealt by 5%. Duration: 10 seconds

Or something like that. Just flinging ideas here.