Question:  Hydra is an album by Within Temptation and contains guest appearances by an American metalcore vocalist best known for being the vocalist of what two bands?

Related documents: [0]  [DOC] Howard Jones (born July 20, 1970) is an American metalcore vocalist, best known as vocalist of the bands Killswitch Engage and Blood Has Been Shed, and as the current vocalist of Light the Torch, formerly known as Devil You Know. [END] 
[1]  [DOC] Hydra is the sixth studio album by Dutch symphonic metal band Within Temptation. It was released on January 31, 2014 in Europe and on February 4, 2014 in North America. The album contains guest appearances by singer Howard Jones (ex-Killswitch Engage), rapper Xzibit, metal vocalist Tarja Turunen (ex-Nightwish) and alternative rock singer Dave Pirner (Soul Asylum). The first single, "Paradise (What About Us?)", was released on September 27, 2013, and featured Turunen as guest vocalist. The second single, "Dangerous", was released on December 20, in which Jones provided the male vocals. [END]  
Answer: Killswitch Engage and Blood Has Been Shed
Killswitch Engage and Blood Has Been Shed