Petrylloc's Gambit

Petrylloc's Gambit is a spell that creates a wall of ice and two walls of stone above a target, which then fall upon it. It was cast in a group casting in 1374 DR by Khelben "Blackstaff" Arunsun and the wizards Sememmon and Ashemmi in order to defeat a sharn at the Sleeping Dragon inn.