Honestly they should just remove the death penalty from Walking Dead and instead make it so that all of DRK's attack's lifesteal HP back while being invulnerable to damage but can't be healed for the duration. As long as each attack heals for 75% of the DRKs damage potency, it wouldn't be hard for DRKS to get back to 50-75% HP. Having a visual effect to let healers know that they can't heal the DRK by having some sort of bright purple aura around the DRK would allow them to ignore the DRK for the duration of Walking Dead, this way it would actually help healers save on MP and have the skill rely solely on the DRK's own abilities and resources to get back to a healthy position.

The fact that Living Dead requires a healers intervention and taxes them, is part of the reason why it's considered a bad invulnerability skill. If I used Living Dead and died to Walking Dead then it would be on me for not using my resources to get myself back up to a healthy HP line. Currently Living Undead punishes both the tank and healer if all requirements aren't met and I hate having an ability that puts pressure on my teammates.