Resilient Sphere is a great lowish level spell for trapping someone within an inimical effect. If they haven't got dispel magic or one of the ways of bypassing a wall of force, they are stuck inside for 1 min per level.
Particularly nasty if combined with Cloudkill, which even high level characters are threatened by - 1d4 CON damage per round, Fort save for half. If you haven't got someone to rescue you from the resilient sphere that is at least 9 minutes breathing cloudkill... 90 rounds, so you are guaranteed to take at least 90 CON damage, and probably more (especially as your CON degrades due to the poison!)
You've got to fail the Ref ST against the resilient sphere, but if you do it's curtains (unless you can teleport/become immune to poison/find dispel magic!)
Cheers