He was asking about Blood DK, which means that it doesn't have Unholy Blight (that's a hybrid), so against that you can spam dispel and be done with him easily.
I'd still disagree, sure spaming purge and all that is cancer vs ret, and you can faceroll a ret if he fights you with a 2h weapon. But when ret is using 1h+shield, it isn't as easy, I basically tank them until they go low on mana and then it's GG (Spaming purge usually leads them to that). And I've fought many Enha shamans, sure it's not impossible to lose, it happens, but I never got completely destroyed by enha.