Fight caves-jad-Runescape?

I would like to know the optimal gear i would need to get a fire cape.. Can pretty much wield anything and money isn't an issue.. What would be the best and easiest gear to be able to get it.. I'll be using a rune crossbow but what bolts? I see everyone saying to use diamond bolts (e) why not go balls out and use onyx bolts (e)? I assume onyx bolts (e) would be better? Perhaps dragon bolts (e)? Let me know! Thanks!