Shadow ruins easy adv points.

[resto69]

When in the room with the floating things (whatever they are) and the four athena nights at the four corners, jump on the floating thing making the widest circle...jump into either of the rooms. Once in the room, head back out. You'll be able to come out of the room and onto the very top of the pit. Face either athena knight and start hacking away. If you knock them back a bit, inch forward and continue. They will take a while to beat with standard weapons, but the adv points are worth it (300,000+ per knight). Also, once you have defeated one of them, acquire their weapon (a stone mallet) and use that agaisnt them...it works wonders. Enjoy!

[darkpark]

yep! lots of experience points here but there is also another room that contains six of them. those give you around 450k xp/adv points.
i gained like 3 levels by killed every athena i could find. i was level 29 by the time i made it out.