Derotain Mudsipper

Derotain Mudsipper is a level 52 quest giver located in Gadgetzan in the contested territory of Tanaris. He is a Dark Iron dwarf and a member of the Thorium Brotherhood, and can be found near the city's forge and anvil.

Blacksmiths who have a character level of at least 50 and a skill level of at least 265 can learn how to create pieces of the Imperial Plate armor set. In order to get the plans for each piece, you need to turn in Thorium Bars to Derotain.

For each turn-in, you will get the plans as well as reputation with the Thorium Brotherhood (+1150 reputation after getting all 7 plans).

He starts the following quests: See List of Tanaris NPCs.
 * (Blacksmithing)
 * (Blacksmithing)
 * (Blacksmithing)
 * (Blacksmithing)
 * (Blacksmithing)
 * (Blacksmithing)
 * (Blacksmithing)

In Cataclysm
In Cataclysm, he no longer offers these quests. The patterns are learned directly from any Blacksmithing trainer. Belt, shoulders, and bracers are trainable at 265, the boots and helm are trainable at level 295, and the chest is trainable at level 300.

Trivia
The disdainful attitude he gives players comes from the expected, and generally accurate, reaction to requiring such large amounts of Thorium for the plans. Though recent patches, not to mention two expansions, have expanded available Thorium to players, these plans are still amongst the most expensive to acquire and create. At one point, before a patch reducing the cost, acquiring and crafting the set required 384 Thorium Bars. For this reason, being able to craft the entire Imperial Set was once considered an impressive feat undertaken only by the truly dedicated or insane.