I would get roof from the back, gas/acid all the thralls out on the claws then just start drilling a hole straight down through the middle using explosive jars (solo raid, 1 thrall, encumbered build)
Easy base.
Edit: once on the roof lightning bolt that fkr and hopefully takeout the map room.
Just for fun it would be highly entertaining stomp around on that thing with True Name of Mitra 
Might wanna get a bubble up