I love Death knights thematically and everything but I wish they would just make DnD/Defile an aura that follows you around like they're doing with the rider of the apocalypse DK that spawns in with a moving DnD aura
Played a lot of unholy, so I'm used to it by now. Very important is to find a UI where it's easy for you to find your running buffs. In AOE situations you basically only have to track 2 things, keep your disease on the mobs and your plaguebringer buff up.