I'm trying out DRK now after the... clunky changes to GNB, I think DRK's mitigations are in an okay spot now, but it definitely needs a boost on the self-healing side. I would add some self-healing on Edge/Flood of Darkness/Shadow and TBN. I think there should be a weaker version of TBN that should come in at a lower level (it basically works like it does now). TBN should be buffed to heal you the amount it shields (kind of how they have Thrill of Battle set up where it gives the Max HP boost and the heal later). I don't know if this would break TBN, but I think the cooldown should be functionally removed (reduced to 7-or-8 seconds). It already has an MP cost, so the skill already has a functional cooldown tied to your MP generation. It doesn't feel good that, when you go all out for your burst, you might not have a shield available for tank busters or other mechanics.
Speaking of MP generation, I feel like Quietus/Bloodspiller/Scarlet Delirium combo/Impalement should have their own MP amount regenerated. It feels weird to me that they don't. I could be wrong as it's been some time since I've played DRK, but didn't Quietus/Bloodspiller used to have MP generation on their skills?
One mitigation buff I think would be fun is for Oblation. Functionally, it's fine, but it feels underwhelming. I was thinking of adding something like Blood Price to the skill: Every time the person with Oblation is struck, they regenerate a bit of HP (instead of MP like Blood Price used to do). Personally, I think Salt and Darkness should also regenerate HP like Abyssal Drain (and maybe make Salted Earth a skill that activates under Blood Weapon/Delirium like Sonic Break. The 90s cooldown is just weird).
I'm sorry if these are bad ideas. I've only recently picked DRK back up, and I haven't played it seriously for several expansions.