Board Thread:Questions and Answers/@comment-25179062-20141215193812/@comment-5007614-20141215211256

I would expect it to continue to get more and more difficult, from I have found that SBB leveling difficulty appears to "reset" when unlocked. This is purely based off of my own personal experience.

I use Burst Frogs when at BB8 or 9 to unlock SBB, then level with fodder units again. I got lucky with Rina, going from BB1 to SBB8 in 16 levels (using just Mistral fodder units), where I was unlucky with Faris who went from BB1 to BB7 after 22 levels - no SBB unlocked!