Power Stone Optimization.

I have found out, to my dismay, that there is a clear cut way to optimize your Power Stones.  When I obtained my first Ophelia I got excited and power leveled her to Shield Tier and did not think about Power Stones...  I then pulled one from Supreme Summons the next day.  This spurred an experiment that had me a little upset.  It now takes 6 Power Stones per stat increase.  When I went to boost up my Level 1 Tier 1 Ophelia it only cost 3...  This means that if you save up your Power Stones and you want to optimize them to enhance your favorite hero, do it before you tier them up.  This way you get the most stat increase benefit per Power Stone.  This may seem like a small deal to some, but it can add up to a lot of stat difference in the long run.   I just thought I would share to help out those who may not know and can benefit.