fire won't be able to do any decent damage against darkness, its creatures will die too easily and darkness will heal while attacking. Vampires with eclipse and crimson dragon have same value for pure attacking, while vampire costs half and has more hp. Also fire must use most likely two fire lances or the more expensive elixir to kill one creature because of pests and expensive creatures like phoenix and the dragon, also making Farhenheit much worse then vampire dagger. Darkness only needs one cc to kill, making it have better cc as well, which is supposed to be one of fire main strengths.