Our party spends a little time trying to find a way either to pass or, ideally, defeat the purple worm. We decide it would be best to defeat the worm, seeing as how this cavern looks to be the only way forwards, because it would clear our escape route should we need to leave in a hurry. Running past this monster's haunt whilst low on hit points and spells does not appeal to us, particularly if we are being chased by whatever drained us of hit points and spells in the first place.
The first part of the plan was on how to flush the worm out of wherever it was in the cavern, so that we could then attack it. Well, so that I could then attack it, albeit from the ceiling of the cavern, pelting it with arrows with the aid of a fly spell. What can I say, it was the best we could come up with. On how to get the worm's attention the Paladin came up with the idea of summoning his mount and getting that to tramp around heavily for a while.
Said the Paladin, 'The heavy tramping will get the attention of the purple worm, and when the worm attacks and picks up the mount I can dismiss it and we can start attacking the worm!'
'Um, wouldn't it be better to dismiss your steed before the worm attacks it?', just about everyone else asks the Lawful Good Paladin.
Still, that was just a small detail in an otherwise flawless plan.