Here is an older map I drew that is formatted for roll20.net. It's 3 areas of a large dungeon/sewer filled with caustic slime. There is a duplicate image of the final dungeon room, filled with slime so you can change up the encounter on your players. When I ran it, the devious slaad priest released the caustic slime when the players had turned the tide on the enemies. The slime damaged the players and caused them to think about their movements, and make decisions about how to spend their precious heals. If you have another idea for the slime, drop me a note in the comments.
Alternate Dropbox link
Slime Dungeon - Color