I went in there will neit helm, black d'hide body and chaps, barrows gloves, glory, whip, ruby (e) bolts, rune crossbow super set, prayer potions, and sharks. Killed a Ket-Zek no problems. Didn't spend much because i already wore that as my armor or had it in my bank. Really, it's not that hard. If you need to explore the "difficulty" of the arena then just go in the first time with armor and no food/pots and see how long you last. Then actually go and get through the 32 waves of Ket-NERRRRRRRRRRs and destroy a Zek. Just make sure to range it and stay away from it's melee attack.