Abyssal Drain is the only spell that is a ranged aoe enmity spell. Thus DRK is the only tank that is able to catch groups of ennemies from distance. Unleash is working best has being used right after unmend because of the possible free unleash but also because it costs less mana. Abyssal drain does more damage but has a smaller area of effect. You'll use Abyssal Drain when the mobs are properly packed mostly because in dungeon it's almost impossible to catch every single mob with it.

On A1 instead of having to goes behind the boss to catch adds, I can just use abyssal drain from distance to place them correctly. Will probably find a similar use later on.

In the end this spell doesn't need to be reworked as it works well with the DRK's kit.