If Napalm is allowed, why not just go for Dynamite? (just kidding - sheesh!). Typically, Battlebots are allowed to cut, hammer, flip, etc., but not to shoot out projectiles or release chemicals, etc. For a beginner 'bot, I would think along the lines of a low-profile flipper/dozer, or a vertical high speed saw. I've always thought a 'bot with a high-power EMP weapon might do well in competition, but if I fielded one, the FCC and my employer might both get a little irate.