Beeing undefeatable and 1hitting enemies in 1 person... not possible :-)
If you want to play a tank msot of the "modern" tanks are playing with a magicka build as a DK now, using fire damagee skills were needed.
But you won't be a good tank if you do much damage AND are able to stand in a mob group for hours.
My last tank expereiences were stamina based but as they removed the stamina regen buff if you are blocking this was impossible to play. So currently they use magicka skills, a huge magicka base and regen and filling up their stamina pool by using te passive skills of the DK skill lines (using magicka skills to activate the skills + getting pasive regen bobus etc.)
A tank that I truest told me that she will be able to be infight with bosses for a very long time without getting much heal. But she isn't doing any noticeable damaga (maximum about 7-10k depending on boss's resistances against magicka skills).
So I'd decide for my self if I want to be a long living tank, or if I want to be a 1hit monster.
For the later play the DK with magicka skills, destruction fire staff and fire skills and spend your champion points into attack skills, crit chance etc. and use 5x light armor.
If you want to be a real tank go and find a skill online with magicka build (maybe this is ok for you:
http://tamrielfoundry.com/topic/magi...k-the-spectre/) , heavy armor parts and sets and play with a 2hd weapon during leveling to do some damage (or a deconstruction satff maybe as well).