Thanks for the chapter!
Yes, cold poison for when just regular poison isn't enough to deliver the message. Seriously though, if anyone not familiar with it cold poison is a substance that chills and freezes somebody from the inside rather than using toxicity to damage the body. Since the poison isn't natural it requires either a high rank alchemist to make or to be extracted from a demon beast that uses venom with an ice attribute. If left untreated the victim eventually freezes into an ice statue so basically need a stronger fire based antidote to slow/halt/cure the poison. Cultivation can slow it down a bit but can't halt it. A hot climate and food/drink is just as effective as a small band-aid on a gaping wound.