It's kinda gimmicky though. A frozen 30 hp Armagio only does 4 more damage than an unfrozen one, so it's not worth going out of your way to freeze creatures before throwing them. Same thing with poison; while you can poison your creatures before throwing them, it's better to just poison your opponent directly.
They might be worth using on Voodoo Dolls though. Freeze will also freeze your opponent's weapon, and poison is effectively doubled.