Professor Dabiri at the Protectorate Watch Post in Netherstorm wants you to recover 8 Fragments of Dimensius.
Atop Manaforge Ultris lies the tear in the nether that the void lord, Dimensius, came through. That tear provides Dimensius with a link to the void, rendering him immune to physical harm. If we can get a lock on the conduit that Dimensius is using to keep himself phased out of this plane of existence, we can destroy it and then destroy Dimensius.
To do this, we're going to first need you to collect fragments of Dimensius from the void creatures that he sends out to do his dirty work.