*Edit* To get the Mille Bolle Blue to unlock as a weapon you first have to kill 6000 Kappa they can be found at the bottom of the map by the green river. You can purchase this weapon from the merchant after you unlock it.
To Evolve this weapon you need to have a Level 5 "spellbinder" and a level 8 "Mille Bolle Blue". Opening a chest after the 10 minute mark should evolve this combo. Or you can play until you get a Candybox II and unlock this evolution right away.
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