either go to bikanel (sanubia sands) and fight sandworms or go there capture one (or more) and fight them in the monster arena (quicker way to do this), I found them to be pretty good especially if overkilled with double AP or overdrive to AP. I used these to get ready for the omega ruins which was a big step up (tough at first but just stay within 2 steps of the save sphere) but certainly possible.