Best Tank build is: doesn't matter; hold magic wall.
Yep. Hold magic wall even in melee fights. You can block melee attacks with it for your teammates.
Hold that ish, and don't die by blocking power attacks, and bringing along a priest.
There is no Optimal tank build IMO.
The skills are somewhat lack luster, they depend on your teammates no matter what in the end.
There is this guys build:
http://www.youtube.com/watch?v=JATgym2pSw8