When expanded, is it a 30-foot tall tower, with an additional 10 feet underground for a total of 20x20x40? Or is it a 20-foot tall tower with an additional 10 feet underground for a total of 20x20x30?
I ask because I'm considering having the walls magically treated, as per the rules for Dungeons in the Environment chapter.
When expanded, is it a 30-foot tall tower, with an additional 10 feet underground for a total of 20x20x40?
this, it is explicitly stated to be a 30' tall tower, the walls extend a further 10' into the ground to prevent it from tipping over.
it's yea by yea plus a few extra cubits.