How is this fair for DRK?

[Dracosavarian]

If it break in 3 seconds then that means you just prevented yourself from taking 25 % of your max health worth of damage in those 3 seconds. You are also completely ignoring the fact that you can use TBN cooldown is 15 so it's going to be up way more often than those "far more powerful mitigations".

2 TBN's a Minute. Realistically speaking, with respect to a Drk's rotation. A variable duration of Nullification being up ranging from 2 to 14 seconds of total uptime, that does not heal us, provides no mitigation effects, explicitly tied to a damage resource which is required to fuel it, that must be monitored and held in reserve at the cost of our damage resource...

Vs Bloodwhetting, Heart of Corundum, or Holy Shelltron that has a fixed duration that is actually up and running longer than TBN, costs absolutely nothing for Gunbreaker and Warrior to utilize and can also be used twice per minute, that mitigates damage and heals the user as well. ( And in Bloodwhetting's case, shields you as well )

Bluntly, yes, they are more powerful. And arguably far, far more useful. If a Dark Knight is holding back their mana to fuel TBN's constantly, they are sacrificing something they shouldn't have to.