i'd recommend getting one of the following Bzzt Blaster, Fungus Ray which are 11 iconers but you could also consider getting either a Ramtors Spellbook or Scuzzys Comb which are only 1 icon less but are much cheaper.
the 11 iconers are terrible if you already have an intermeadiate/good set then get a clawed shield(probs my favorite weapon) most people tend to use dual kiln to get through g-sheild and rotl so if you use this then it throws it back at them or get Scuzzys comb + RSB + HP if you dont have a set.
This is a good website for the battledome: http://idb.finalhit.org/. It'll give you lists of items, information about them, and people usually comment on why it's good or bad.