This item is sold by in Shattrath City for 74 33 (was 41 ).
This trinket is designed for Protection Paladins and Warriors.
Protection Paladins have a passive 30% block chance and an active 30% block chance, and blocking is the way Protection Paladins hold threat. High block value for a Paladin is essential to tanking performance and should be given to Paladins before Warriors.
Protection Warriors use the talent granted ability Shield Slam as one of their main source for producing both threat and damage, Shield Slam adds the block value to the damage of the slam, when activated this trinket adds 259 pre-mitigation damage (330 with the talent Shield Mastery) to Shield Slam, and this value possibly stacks with Eternal Earthstorm Diamond making it even better.
The downside of this trinket is that damage mitigation is often high priority for tanks and there are other much better mitigation trinkets available than this.