Bloodmaul Slag Mines is a 5-man dungeon in Frostfire Ridge introduced with Warlords of Draenor.
From the official site
"Some like it hot and others are simply slaves within it. This level 90-92 dungeon takes players into the sweltering heat of active volcanic caverns wherein Bloodmaul ogres run a brutal mining operation powered by the blood and sweat of slaves acquisitioned from all across Draenor. The Slag Mines produce a bounty of gemstones and ore, but it’s rumored that the true purpose of these mines is to dig for an ancient relic of immense power.
Players encounter four bosses and a lot of fire power as they try to disrupt their machinations."