Board Thread:General Discussion/@comment-68.37.163.127-20130131132513/@comment-5816492-20130208015137

The use your 3 strongest characters in the back row and 6 level 1 rank 1s in the front row worked wonders for PvP. You would get large xp rewards about 15-25% of a level for 1 cube used. They changed the rewards though, so you cant really take advantage of it anymore :(

Not sure if he used that, but just a guess.