If other classes didn't deal so much damage within a 4 second span, we'd be looking better. As it stands DKs just need a few tweaks.
Bone Shield baseline.
(4 charges, -20% damage. Glyph for 2 more charges but only reduces physical damage).
Snare/root break on Death's Advance.
Replace Asphyxiate with old Desecration AE snare in the tree. Strange on 1 minute cooldown, 5 second silence, 25 yrd range, no GCD, no rune cost.Lookin' good.
(at most 20 RP).