More CDs like Vengeance would be a start. Spike damage auras or shields would be sexy. And would fill a niche playstyle a Tank could uniquely provide. All based on invoking defensives that actively hurt the enemy just by hitting you.
So much focus on Tanks these days is all about DPS and not enough about defensives.
I'd rather TBN explode if it breaks and does the amount of HP in pure damage on the fool that broke it.
