There was a 'Lair Beneath Phantom Forest' Kickstarter thing where every 1000 backers after that was announced would add one level, which got up to about 10.5 (plus whatever Paypal pledges were made after the kickstarter graphics stopped being updated). When Larian was actually making the dungeon, though, the size became an issue, and eventually a couple of the levels that were not fun / finished were removed, and the rest split up and used in different areas of the game.
