Urok Doomhowl resides in the lower area of Blackrock Spire with a few of his fellow tribe ogres. To summon him you'll need to kill Highlord Omokk and pick up his head, second you need a Roughshod Pike found in the Blackrock Spire and place it on Urok's Tribute Pile which is located in the corner behind the ogres just after the area filled with spiders. It is advised to clear the ogres first before placing the pike as Urok's guards will come before he appears himself.
Urok cursed Warosh and stole his mojo.
- On Combat:
Urok Doom Howl yells: You have summoned me, fool! Now DIE!
Urok Doom Howl says: I'll crush you!
Urok Doom Howl says: Me smash! You die!
He is fearable. So if you have a warlock you can keep him dotted and feared until he dies. Provided you clear the mobs surrounding the area, his adds can be safely feared as well, to make the fight more manageable.
Operating Ommokk's head during the fight causes a lot of damage to his minions. Someone should be assigned to use it as soon as it becomes available (about a 30 second cooldown).