Sursi

From MTG Salvation Wiki

Sursi is a large plateau in southern Aerona and also the name of a village in this area. It is home to a race of pegasi. It contained the only portal from Dominaria to Ulgrotha, which was probably destroyed by the disasters that happened on Dominaria. Using the portal required to pass a doorway made of three "menhir stones" when the Mist Moon was full and snow was on the ground. The portal leads to the Koskun Mountains, home to Eron the Relentless.

On the Plains of Sursi, Serra was attacked by another disguised planeswalker, who thought that her wedding ring was some powerful artifact. Angus took her body and created Cathedral of Serra near the Sursi village.