Originally Posted by
Broken_L_button
If you want to know if Rare boost is worth the 4 slots it's stuffing or the cash you spent on Sayo, follow these simple rules:
-if the item you're hunting drops from:
~any kind of box: Rare boost has no effect.
~From a monster, but listed under the "type" sections: Rare boost helps
~From a monster, but listed in the "common drop" section: Rare boost reduces your chances of finding it (for example, Caduceus from Bal Soza, Satellite Riser from armed servant - Ozuna are tougher to find with any kind of Rare boost active).