I've determined the cause of the instability!
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.
Have you been to the rift in the Nexus?
Excellent work, <name>. The tremors have already begun to subside.
With any luck, your efforts have granted us sufficient time to find a way to thwart Malygos' efforts.