Really? You saying it is too hard?
If you are talking about the first trial, you just need to stay still, the boss will come to your force with two chimera and you will kill them. Piece of cake.
If you want to take the ruin treasures just use the railroad and enemies won't spawn anymore. Easy as that.
Also, that battle is awesome to grind xp of friendship status, i loved that! It's just unusual cause you need to stand still to win it, but when it comes to diversity is always a good thing in a 3 discs game, isn't it?
Are you by any chance using the translated version? Cause when you ask for advice Benetram clearly states to stay on hold on that battle... and that counts for the second trial too, the robots will move forth by 5 squares or stop when toucing someone to turn right. Nothing is really hard there either.
Guess you were a bit bored or in a bad mood, you should try again cause this game just rocks!