Greater Solo Crystals Just Gave Me This Extremely High-Value Item!!!

Hieitaku

Or at least that's how the game describes it. Plain awesome.

KoopaKrusher

I used to use those solo crystals to just get a little extra gold from selling all the boosts that I don't use. But now I can't sell the attack boosts either. Honestly, it's probably a good thing because now I have no reason to not use the boosts, even as just a little PI boost for arena grinding.