Icebox Trap CR 10
Source: Pathfinder Adventure Path #34.
This trap forms a 1-foot-thick wall of ice along every wall (blocking doorways) and reduces the temperature in the room to –30º F for 12 minutes. Once the trap runs its course, both doors unlock, but the walls of ice blocks remain for 12 minutes.
Trigger proximity (alarm); Duration 7 rounds; Reset automatic
Effect spell effect (wall of ice covers every wall of entire room; CL 12th); extreme cold (1d6 cold damage/minute; creatures in contact with exposed metal take an additional 1d6 points of cold damage per round); multiple targets