Destroyer Breastplate

The Destroyer Breastplate is the Tier 5 Warrior DPS chestpiece. It provides a bonus to strength, stamina, hit rating, and critical strike rating. It is part of the Destroyer Battlegear set.

Source
This item is sold by in the Seer's Library on the Scryer's Tier and by  in the Shrine of Unending Light on Aldor Rise in Shattrath City. The cost of the item is a Chestguard of the Vanquished Defender token.