Indeed, Ice devils escape it quite easily, if not even a quaranteed 100% chance to escape. Tome of Lower Planes also gives you some more +% to escape at least, like Gregstorm said about artifacts. I wonder if boots of the planes do the same. Either way, Claws of Kokytos and the fire version are a very powerful anti-sc/thug tools, but they don't actually kill the unit, like your pan there
