Why would TBN need even that? You'd need to take what would have been 118% of your max HP over HoS's duration for HoS to actually absorb as much damage as a TBN, despite TBN being on a cooldown only 60% as long. And, they're both free, unless you use TBN stupidly. TBN is absurdly powerful right now, with its only real issue being one of scaling -- eventually no longer being able to pop it when badly overgearing dungeons because it just absorbs so damn much. It, should, by all rights, be reduced towards more like 15% HP on nearer a 25-second cooldown if we're looking for parity...
Don't get me wrong, I think TBN needs its 15s CD; it keeps it way more engaging to absorb the skills between the skills others can absorb with their 25s skills. But, I wouldn't be sad to see it be cut down to 20% HP or even 15%.
And, in the meanwhile, just looking forward to Living Dead being made more intuitive, a Dark Mind adjustment, Abyssal Drain doing far more at low target counts without losing its AoE scaling, self-healing perhaps getting moved to Bloodspiller (and more significantly) for ease of timing, and --above all-- not arbitrarily having certain tankbusters snapshot our mitigation sooner than others (so that if TBN at .7 seconds or so (+ ping) before cast-finish works on one skill, it works on all others, too).
