Someone from the reddit thread suggested what I feel is easily the best solution to Living Dead. Simply put, you take zero damage but also cannot be healed throughout its duration. So if you active it with 5% of your HP, you'll stay at exactly 5% for 10s. If you active it at 90%, you'll stay at 90%. Not only does this allow DRK to feel powerful using its own invuln but also removes the resource dump required from Healers. This also justifies the 60s longer CD than Holmgang because you're technically immune to damage.

Basically, this fixes nearly all of LD's problems in one fell swoop.