Near as I know, only one power is a hold and ONLY after it's given an advantage to do so, it also lacks any real theme to it, only seems so incidentally. Everything else causes root, to be specific, Wall of Ice and Ice Cage CAUSE Ice Cage (Root) while any other power in the set has a chance to apply chill and as such has a chance to trigger an incidental Ice Cage, in the same way Hurricane can when you add it's advantage cause the cold damage there causes Chill and chill might cause Ice Cages. I assume those random, possible Ice Cages are also a root and not just for show.