Coren Direbrew is located inside Blackrock Depths at the Grim Guzzler, and you can easily access him from the teleporter device that is on the right side of the entrance.

He has 160,000 HP and is pretty easy to take down. He starts out with three non-elite adds that the tank should pick and up and the group should take them down quickly.

Coren himself can disarm the tank or anyone in melee range and will also do a whirlwind attack. Just watch for the drills that pop out of the floor. They will throw you in the air and spawn adds. Assign someone to kill the adds and you should have no problems taking him down! Also note that at 66% and 33% he summons his barmaid. Most groups are able to ignore her so long as they tank grabs her aggro. The barmaids throw Beer Kegs at random players that disorients for around 5 seconds. If the tank gets "Kegged" you could have a problem.