The Lamia's Spring

Water is the most precious resource in this parched landscape. The oases have all vanished and wells are beginning to run dry. A pride of Lamias have made claimed this ancient spring, buried deep in a desert cave, knowing that their prey will now come to them out of necessity. Some brave locals have attempted to traverse the sandy passageways and echoing drips of this cavern to claim a small jug of water. Most do not return. Will the party help this desiccated land rid itself of this new threat?

What group or monster would you have inhabiting this cave? Tell me in the comments!