Originally Posted by Mystic

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Make 8 Lv 1 + Lv 1 = Lv 10 or 11(if you get a great synthesis success) [8 x lv 1 upgrade cost]
Lv 1 + 7* LV 10 & 1 Lv 11 = Lv 30 [8 x lv 1 upgrade cost]
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Wow thats nifty. It will also allow me to 'upgrade' my crappy stuff (though just to Lv 10) without a second thought until I don't need them anymore. Just as Astasia said, for now I still have to use the medicore stuff.

After testing it a bit, it seems that the amount of sacrificed items is just as important as their level:
- Lv 1 + 2 x Lv 20 = Lv 21 (sacrificed: 22 x Lv 1)
- Lv 1 + 1 x Lv 20 + 9 x Lv 1 = Lv 25 (sacrificed: 21 x Lv 1)

This would mean that the most effective upgrade method is to create throw-away items with such a level, that you will need exactly 10 of them to max a high end level item in one try. Looking at your example that would be level 9 / 10 items for a final level 30. Understood!

Btw. would the same principle hold for upgrading the girls level using 2* girls as an alternative to manyus? Just combine 2* girls to level 8 and then fuse them with other high level girls? Or is it still not worth the coin cost?