Cannonable specters, black mask on dust devils, and the extra armor. It's really only something for someone who really trains slayer, not for someone who is plowing through level 20 bears where its bonuses aren't worthwhile. The slayer rewards from smoking kills are extras, bonuses for training slayer that makes it easier, not necessities. I wouldn't get the helm unless you are seriously training slayer and using either Sumona or Duradel full time.