Lyrthindor

Lyrthindor is a secret Dark Justiciar in the Gauntlet of Shar. He has hidden himself from Yurgir by separating himself into the many rats that are scattered around the gauntlet. This has inadvertently prevented Yurgir from completing his contract and thus killing Lyrthindor is one solution to Break Yurgir's Contract. To get him to appear you have to attack the rats around the Gauntlet of Shar.