I'm not arguing over petty things though. The Pizwah wasn't paying attention to his DPS and he still managed to outDPS you, with a lower ilv weapon no less, when you were bragging about DRK being better than WAR... . That was what I was trying to point out.
Also you claim people still don't know how to play DRK, but DRK is really simple, it's a reskinned PLD with the same CD structure as PLD (1 CD with 90s and 1 with 180s and 1 uber long bad-version-of-I-won't-die CD + other CDs to cover gaps). DRK micromanagement of MP and oGCDs are mainly DPS things that don't contribute much for defense and there is no micromanagement mitigation (Like WAR's wrath and IB for example). Please let's stop pretending any of the tanks is "too hard" to play and people can't learn to play them. Hell it took me 30 minutes to read through DRK skills and understand that it's a PLD in a dark spiky suit playing pretend-WAR.
DRK is the worst tank in A2S because, out of the three tanks, it has the worst mitigation options while not bringing that much in terms of DPS compared to WAR (who has far superior mitigation options in this fight). PLD is king in that fight because of how well it mitigates damage in there and its ability to use HG on the toughest waves.
Now on topic, Unleash is useful, Abyssal Drain is only a DPS increase if MP is not an issue (and in A2S it is). But there is almost no point in having both.
Yes, every tank class has 2 AoE skills that generated ~600 potency enmity. PLD with Flash (600 potency) and CoS (250 x3), WAR with Overpower (120 x5) and SC (200 x3.5), and DRK with Abyssal Drain (120 x5) and Unleash (100 x6). If you look at each class you see that their 2 skills work differently. PLD has a no damage MP PBAoE and a DoT PBAoE on a CD. WAR has a cone AoE that costs TP and a PBAoE that costs Infuriated. But AD and Unleash just don't function very differently from one another and that's why they feel redundant. Both use the same resource, both generate exactly the same enmity. One of them having an added effect at the cost of triple the MP (DA+AD is almost triple the MP of 1 AD) just doesn't cut it.
IMO, remove Unleash, give Abyssal Drain the ability to not break combos and add enmity to Salted Earth and give DRK 1 more CD or something in place of Unleash. Or make Abyssal Drain ALWAYS "Drain" 50% or even 25% of its damage and have DA up that to 100%.