Room 4/28 is a heavily damaged gazebo sitting in a small lot. Every 4 hours (subject to revision by me as I think things through more), a ghostly goblin band starts loudly playing music to dance to. The music summons up 1d4+1 Fiery Licks, who start to dance and burn things ups. A few rounds later, 1d2+1 Water Elementals are also called, and the two groups battle till one is destroyed. Then band and music fade shortly after.
The band and music are on a cycle thanks to a Recurrence Rune scribed and stashed in the gazebo. Until it is removed, the music comes like clockwork, summoning more elementals to fight.