Isn't obvious on maps how to get to the frozen basement. You need to go thru the Chetari tunnels (the dracoliches see thru invis, FYI) and exit at the top right. You'll pass into one of the dragon fire regions. From there you'll see a tunnel spilling some ice into the fiery area. That's the tunnel to the basement where this named spawns.
There is a route thru the Chetari which avoids SI dracoliche skells, basically make your way to quest mob Oaxy, head east toward where Zalifur spawns and turn south from his area. Then take the left that runs to the vertical tunnel to the fire area.