First goto the guardian tower and then goto the teleporting area and then click
battle carnax and then u will battle carnax and u must battle about 4 or 5 carnax
i think and when u beat 1 of them ull get 1000+ xp and 500+ gold! 
If u battle 5 carnax ull get 5000 xp and 2500 gold !!!!! and if u only battle 
4 carnax ull get 4000 xp and 2000 gold!