I'm an arcane mage specced and geared for PvP. I have almost 1300 spell dmg and about 21% crit if I recall correctly. I have 2 pieces of deadly and 7 hateful. My resil is at 750.
A friend of mine with very similar gear (I think he has 3 deadly) is a DK and dueled me just now to test out his new build and his new resil trinket which procs 3 times giving him resil of 910 or something. During the duel he didn't use his ghoul and didn't attack me at all other than that frost attack that slows me. I popped my mirror image to buy some time and blasted away with arcane blast a couple times, hitting arcane missles whenever it proced for rapid fire. I used Arcane Barrage and my gnomish lightning generator and beat him down to about 25% whereupon he started healing himself. I kept blasting realizing he wasn't really fighting back and he just kept on healing. I ran out of mana, went invisible and evocated behind a tree. Did the whole thing again. I burned three bars of mana blasting him and he didn't bother attacking at all until the end.
People have told me DKs were overpowered, but I refuse to believe the situation is this bad. I just had to be doing something wrong. I've never played a DK so I don't know how the heal works exactly. Should I have counterspelled when they're low to prevent healing? Does that work? Is their healing based on something? Can I spell steal anything that might help? The whole situation was rather humiliating (the guys' kind of an *** anyway...this doesn't help his inflated ego).