Fire and Ice are two hidden opponents in One Player Game.
The Fire&Ice moves are described for each separate bot in the HAR area.
Fire: is only available from the Fire Pit arena. And you can only get to him by executing a Fire&Ice move after a destruction. Fire is only available at Champion or higher difficulty, Fire has the 3rd enhancement for Katana, and use the Katana special move Fireball move.
Ice: After defeating Fire you can do a Fire&Ice move again to get to Ice. Ice is only available at Ultimate difficulty. Ice has the 3rd enhancement for Shadow, and can fire the Icefreeze.
Fire & Ice Screenshots: