Also present was a scroll with the instruction "Sprinkle to defrost", which dungeoneer January misread as "Sprinkle to deforest"! Both she and her advisors went on to call the substance 'Deforest Powder', but still realised they needed to take it, thus avoiding a repeat of the potion/poison mixup that did for Team 11 of Series 2.
The powder was used to reanimate Sidriss, who'd been frozen on the spot by Lord Fear (possibly masquerading as Harris) in an attempt to manipulate Hordriss.