I've finished level 920 so created a new account to start all over again. Here's my question... is the only way to add strength to an artifact adding stars to what they "specialize" in? For example, in my new game, Cleobretta has 134 out of 135 stars (to be at full strength). I've got 3 stars on every level of levels 51-95 and I've played her successfully beyond that but seems to be stuck at 134/135. I'm guessing that I used a different artifact sometime during 51-95 when I should have used Cleobretta? Is there no way for me to get her to full strength now?