First of all - credit to
@TheDaywalker for raising two critical issues to our attention:
1) DDHK does not get an Attack bonus from the non-Damaging debuffs.
2) DDHK gets a 5% reduction from TOTAL Attack every time he gains a non-Damaging debuff:
Bugs in action:

Other bugs:
3) Apparently, DDHK’s sig was bugged and supposedly fixed in V34.1, but this is yet to be tested. For more details follow the link and go to the Bug Fixes section:
https://playcontestofchampions.com/news/v34-1-release-notes/4) And lastly, DDHK’s synergy with Masacre ‘Spiritual Strength’ is bugged, he does not carry half or any of his Combo Meter between fights. Remember, Combo Meter is DDHK currency.
These bugs exist on top of his abysmal regeneration rate and relatively short buff duration, but Kabam are happy with where he has landed.
No matter how you try to look at it, this is not acceptable.