Icicle◆ (concentrate) Until the next time it acts, the icicle snake appears to be an unassuming icicle. It has an automatic result of 27 on Deception checks and DCs to pass as an icicle.
Source: Pathfinder Monster Core 2
Running this fight? Add the icicle snake to the initiative tracker: type its name and the AC, hit points and Perception for initiative fill in, and the book button shows this stat block mid-fight.