DRK feels super squish in comparison to the other tanks

[The_User]

ToB contributes to your eHP but it simply isn't mitigation, this is not some kind of alien concept.
Unlike TBN it doesn't actually reduce the damage you take. It makes your HP bar 20% bigger so you're less likely to get oneshot, but you still take the full damage without additional cooldowns to actually reduce it.

You're implying the damage you take while ToB is active didn't have to go through your defense but it only have to when you use TBN?