Accept the risk and trigger it

Diana bites her bottom lip, unsure of what to do, "I fear what these things might do, but {if Tyra’s dispel magic uses left: = 0}you're out of Dispels, so we have little recourse but taking it on the chin..{else}I'd hate to waste your dispels unnecessarily and risk being without them when it counts...{endif}," She looks coyly at Tyra, "Surely we're not going to turn back this early?"

Energized by the jab, Tyra responds "Nine hells to the no!" and brazenly steps between the sigils, daring them to do their worst, which they do.

There is a slight crackle in the air and the telltale fizzle of a spelldischarge. The adventurers stop in their tracks, their arms hanging to their sides and their expressions turning blank, staring into the distance. They’ve just been stunned and will be unresponsive for a little while, eyes glazed over, only retaining enough function to not tip over onto the floor.