After killing Ketheric Thorm and finding out you had the Prisim, you've been on Gortash's radar.

When you arrived in Rivington, the Steel Watch granted you special entry. Which was odd, considering they weren't letting anybody else in. They guided you into the inauguration room, where the Lord stood before you.

"Ah, my special guest!" He greeted, walking down the stairs to greet you properly. "The Prisim bearer," he hummed in amusement, "I'm surprised that you actually survived General Thorm."