Emperor Thaurissan is an encounter inside the Blackrock Mountain set of Mercenary Bounties.
This bounty can be picked up from the Bounty Board and recommends a Party level of 30 to complete it.
You can unlock Emperor Thaurissan by first completing High Justice Grimstone.
Completing this Bounty will unlock the Garr Heroic Bounty.
After this is damaged by a Fire ability, restore that much Health to ALL characters.
Potential Emperor Thaurissan Bounty Rewards
In addition to earning Mercenary Coins based on your Party members, Bounties are assigned to specific Mercenaries to allow you to target loot better.
The following Mercenaries can have their loot appear in the Emperor Thaurissan Bounty: