Can someone explain to me what this is? It's one of the exchange items available in the "Advent Battle" event that is currently going on. From my understanding, it isn't used to upgrade any unit I have, both Ediolon, and Hime characters, or weapons. Can't be exchanged on any page. Nothing.

I got it in the Advent Battle vs Apocalypse and was wondering if there is even a point to getting it again for Phoenix.

Thoughts?

Also, Can someone also explain to me how you "+" Ediolons? I have a few +2 and +3 and I haven't figured out how yet.

Thanks.