I believe pestilence can be used to refresh the duration on all but the primary target, so at least while you're AoE tanking you can refresh the debuffs on everything by spending a pair of blood runes and leaving your death strike runes up. Of course that doesn't adrees the problem when tanking a single target.

Yes, pestilence currently can be used to refresh the duration on all but the primary target. However, there was a glyph (it was actually Glyph of Disease that I was thinking of) that refreshed it on the primary target as well.

"Your Pestilence ability now refreshes disease durations on your primary target back to their maximum duration."

was removed in patch 4.0.1

I *believe* you can use necrotic strike to refresh diseases on your primary target and pestilence on your secondary targets? Can't remember what the rune requirements are though.

Festering Strike increases the duration of the diseases, so yes that could be used to "refresh" your diseases. But that's 1 Blood & 1 Frost rune to use that, plus another Blood rune for Pestilence. Not always a viable option.

However, the point of my original comment was to simply highlight that we actually did have what was being suggested at one point and had it removed.

Necrotic Strike absorbs healing on your target. I believe you meant Festering Strike.

Festering Strike requires one blood and one frost. Using that in blood is pretty detrimental. Not only would that waste a blood rune that you may used on Heart Strike or Rune Tap but also lock you out of a Death Strike as they requires Frost Runes. And to be effective, Festering Strike has to used ever 6 seconds. For unholy, that's fine. For blood and frost, not so much.