Phallon moves back to the south wall.  While moving, Arvak gets to make his melee attack first.

He brings the hammer down (16): 9 9 = red.  BD14-4ac = 10×5 =50 points of damage.  Squish.  Its very dead.

Phallon and Ragnor get into position, but see that the shroom is gone and are able to hold their fire.

Combat over.  Besides the dead shrooms, there is a lot of wrecked furniture and debris strewn around the room (which you haven’t looked at closely yet).  No sign of Dr. Zeebo.

What would you like to do now?