It's a 25%-scaling MaxHP Shield that gives you back a damaging skill when broken. That's quite strong.
And Oblation is a defensive mitigation, and you get 2 stacks of it. Paired up with TBN and this is honestly pretty cool too.

My personal problem with both TBN and Oblation is that Oblation's got a long cooldown because you're expected to have TBN... but TBN has a cost. Sure, it's refunded, but only if it breaks. And while proper use of TBN ensures it will, the fact that it has a potential to not refund the cost + the fact that the cost implies you can't spam it makes me feel like Oblation's cooldown is a little on the high side.

TBN is strong for what it does, and Oblation is nice for what it does. I assume they can be improved upon, but there isn't much you can do to these skills that won't interfere either with eachother or with other parts of their kit. Even just merely making TBN have a Haima effect isn't a good idea, because it scales off of 25% Max Health, and it can be used on other people. It's not a fluctuating value like crit shields from healers are.

imo if DRK wants sustainability like other tanks, either Abyssal Drain should be a bit more accessible (which will interfere with TBN and Oblation a lot), or Stalwart Soul can give a very small heal when it hits anything. Not "per enemy", just proc on use. And that will interfere with TBN and Oblation also, but at a lesser scale. And let Abyssal Drain be the per-hit heal.

My real question is about Dark Mind. Because it's great to use in magic tankbusters... but what if you're in a physical-heavy fight? You're just gonna use Shadow Wall for hard mitigation? Sure, paired up with other stuff of course... but really, that's the only other answer we got? Better than nothing, I guess, but least Camouflage doesn't just give a Parry boost. But that I agree is just me asking dumb questions and derailing the thread a bit.