This mechanic will be difficult to tune and might possibly need to be changed altogether to work.
Healing Absorption: When you heal yourself, you’ll receive an additional effect that absorbs incoming damage.
It sounds like an intended DK analogy to shield block or savage defense. Those abilities always offer damage reduction, based on a simple probability which has no conditions. If you block or crit, you gain the damage-reducing effect. There is no secondary test about whether you were at full health or not. Both are remaining in Cataclysm, with some tweaks we know about.
Healing absorption, the new thing for DKs, has issues when you over-gear content, and maybe don’t take much damage (so therefore don’t self-heal) so in turn do not gain the benefits of this new mechanic. If a DK’s survivability gets balanced around this new mechanic, then we might again feel squishy in 5-mans.
Then in raid content, its benefit is subject to the variability of: whether or not your rune availability for a death strike coincides with you needing heal, and thus gaining the healing absorption. Again, very hard for Blizzard to balance because it’s subject to unpredictable variables (as opposed to block or crit, which are predictable depending on gear levels, and therefore easier to balance).
I’m not so convinced it should be based on healing done, so another derivative might work better, such as parry chance.
Edit: readers cleverly pointed out that this absorption mechanic could work if its benefit was calculated off the full heal value, including overheal.
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