Delete all enemies from a stage
First, use the Cyber Elf that turns all enemies into Metalls. After that, use the Cyber Elf that deletes all small enemies. Since all enemies are Metalls, they are considered small. The stage is now enemy free. Note: Make sure you use the two elves during a mission. Using them on the normal map would be pointless, since they all return once you turn off the game or complete a mission.