On my imperial DK I run:

Bar 1- pierce armor, absorb magic(s/b morph), green dragon blood/vigor, spiked armor, igneous shield, DK standard

Bar 2- inner fire, shield assault, low slash(ultimate regen morph), burning talons, eruption/caltrops(group taunt to a point), corrosive armor or dragon leap(shield morph)

10 magic, 29 health, 25 stamina

Armor master(slot heavy or light armor skill for harder dungeons/trials), 2 PC willpower, 3 piece endurance, 2 piece engine guardian. Big armor pieces have magic glyphs, small get stamina. Jewlery has magic regen glyphs.

Switch between the serpent, the atronach, and the steed mundus.

CP is heavy in block cost mitigation, some in resistances, heavy in magic regen/cost reduction, heavy in healing done and DOT effectiveness/fire damage.

Lol I was just about to link those as they're what I started mine as and have altered it from there, what I've achieved is just more damage for me and group but at the cost of durability so I still find I revert back to this for any particularly tough content or when in a slightly less well oiled group.

Please don't link bad builds. Any tank using 8 skills out of 12 available to him has only some idea of what he's doing.

I run what I'm learning is an oddball build, but it works. Magicka DK regen based tank; dual S&B. I run at ~30k health with tri-stat regen drinks. Mundus is serpent.

I'm not a champ DPS when I switch to light armor, but can pull around 12k and easily close portals in vWGT and health is at 19k. (I think if I switched to green magicka food then my damage would go way up, but haven't really had a need to try it.) If I were running a build that relied on tri-foods, my damage would probably be significantly higher, but right now I have low reliance on external resources.

5 piece Armor Master
5 piece Trinimac
2 Engine Guardian

My focus is on not just normal tanking duties (aggro, debuff, buff), but adding support with the Trinimac heals and shielding other players. I keep pondering switching to Lord Warden, but my only helm is medium well-fitted.

To that end, I'd like to run 5 piece Lunar Bastion, 5 piece Imperium, 2 piece Lord Warden, and then I could drop some points from health back into magicka. But life's too short to grind gear.