All tanks have lost about 30% of their damage in PvP post 3.2 (estimate)

[Nalien]

You're right about Abyssal Drain. It's a can of worms. Sadly, I don't think that there's much that they can do to make it more useful in PvP. It's too situational, and the base dmg would have to be jacked immensely to make it viable in small format fights like Feast ... I just don't see that happening.

Could they not work it similar to Holy/Gravity/Flare? Reduced potency for each additional target. Then we can technically have a stronger 2~3 person drain, with it leveling out to the same numbers overall on larger groups. Always figured that's just how it should have been for PvE even.

As far as the potency goes, they could always just jack up the % returned. Rather than 100% of damage dealt back as HP, we could have 150% back, for example. Actually, a combination of the two, perhaps? On a single target, you get a larger % back as HP. More targets you add, the less % you get back as HP. It's still a 120 potency on-target AoE, just rather than getting 120 potency heal out of it on a single target, perhaps you're getting 240 out of it, throw in another target and it's a total of 240 potency damage with 360 potency healed. Get to three people hit, and it's 360 potency damage with 360 potency healed, as it is now. IIRC three targets is about where it becomes stronger than Grit Souleater (assuming you're not in Grit for Abyssal, at least).

That said, it doesn't need to be useful in PvP. Plenty of skills aren't, granted most of them are tank/enmity related...