Thanks for the responses you two. Should have saved a lot of my SC's on my second run of premium summoning as I didn't any Plats or Blacks. I guess I got lucky with Olivie as my first pick and my first premium run with 75 SCs.

I have another question. What class does Mikoto substitute for? I heard that she is a mix between witch and mage and the beginner's guide said to use 2 witches and 2 mages. Should I still add in another witch to my team or is it okay to sub Mikoto in for a witch?

In your opinions, which Rogue should I focus on if I decide to level them up?