Archmage Berinand in the Transitus Shield wants you to use the Interdimensional Refabricator near the rift in the Nexus.
1x Interdimensional Rift Stalled
I've determined the cause of the instability!
Azeroth's ley lines are being redirected to the Nexus. It's fascinating! If only I could spend the remainder of my days studying this anomaly....
Sadly, I must focus on the immediate crisis. The influx of arcane energies is tearing a rift between dimensions.
Deep inside the Nexus, the fabric of our universe is being weakened. I cannot stop it, but I've discovered a way to slow it down.
Take this into the Nexus and activate it near the forming rift.