i use blood with a few points in frost. combine that with unholy presence and i can jump from mob to mob. first kill is a little slow but after the chance on hit affects proc and i keep going it takes an average two heart strikes, and two obliterates to kill most mobs my lvl. i dont know much about DK tanking specs though. i dont plan on tanking with him (thats what the warrior is for) so i wont bother trying to figure it out.