Currently Delirium is too similar to Inner Release, and Bloodspiller to Fell Cleave.

1. What if DRK got a fallow up combo action after using a Bloodspiller in the form of a new GCD? So whenever you'd use Bloodspiller you'd have a combo GCD to use it into. Same with Quietus.

-> Bloodspiller changes to Bloodspiller II upon execution.
-> Quietus changes to Quietus II upon execution.
A new animation would be pretty cool for both. None of the fallow ups should cost blood gauge, so you can use them outside of Delirium too if you wish.

2. Carve and Spit , Abyssal Drain cooldowns lowered to 20 seconds. Both would benefit greatly if used more often, especially the latter in AoE situations.

3. Put Dark Mind to upgrade into Oblation at higher levels and save 1 hotbar slot.

4. Bring back some form of sustain or resource generation in the form of old Sole Survivor or Blood Price. A great idea I've seen is for Blood price to store up damage ,and when the effect expires or upon a 2nd activation, you are healed for a % of damage taken.

5. Move Dark Missionary to level 70. UCOB and UWU are absolutely horrible without it.

6. For new traits, Esteem can do the new combo GCD off of Bloodspiller and Salted Earth's AoE gives you a 15 second heal over time that lingers on you even if you leave the effected area. Salt and Darkness heals you for 10% of damage dealt + 500 potency.