"That brown dust is a form of mould, and it is what has made this passageway so frigid," explains the arcanist. "If you get too near you could literally freeze do death in moments. Now, I think I have a way of dealing with it..." Olrich's voice trails off as he reaches for the bag containing his book of spells. He flips through the pages for a few moments before settling on one and scanning it for a few seconds. Those watching carefully might catch a small glimpse of energy roiling in his eyes as he does so.
The arcanist closes his spellbook and holds it to his chest with his left hand while he steps up to the ledge. He makes a few gestures, says a few short words, and then points at a patch of mould as a thin ray of icy white energy bursts from his fingertip to strike at it.
OOC: Use my quick study exploit to swap out jolt in favour of ray of frost, and then cast it.