The first time i got BUTCHERED by my DK, he had LOADS invested in deathblow.... which is exactly what it did to me, 1 in 5 - 10 hits he gave me, drained my health down to a sliver. I got killed, relaoded, unlearned everything.... and i had a fair chance against him, since he now only took 20% of my health with every hit, and not all of it every few hits inbetween...