Thazar |
A few easier suggestions would be to have some random pugs running around inside the house to hamper players.
Additionally you could expand the set piece to include some regular salamanders (replace the flamebrothers) and the leader be leveled a bit. Also give them a foot hold in part of the house where they have a contingent in two or three rooms near the tunnel. This will force a bit more of an engagement by the players in the house itself.
Finally you could add a level to all of the Carrion Guards and include a carrion initiate with each patrol.
These three things will make the upper levels tougher... and the final fight at the lower level is already very tough. Just have both the Carrion King and Thok Tal fight the party together.