Dimensional Den

From the introduction:

A wizard is known as Ulter, the “Southpaw,” who discovered the terrible secret of traveling with portals. However, because it was mighty magic, he was unable to control it and ended up creating an area of instability in his old magic laboratory. Ulter is gone, but rumors that in his laboratory there is a legendary treasure, as well as the secret of this powerful magic, have attracted adventurers. However, a curse remains on the spot: each time an adventurer explores it, the place is never the same, and if this treasure exists, it seems that Ulter has disappeared with it. Is the challenge launched, ready to take a chance?