Question about [Nutaku] Taimanin Asagi: Battle Arena

[Thetrueredking]

I just started this game and I'm a bit lost.
I have some cards Sabato Kiryuu
They seem like other trash but I notice they show EXP. Do I do anything with these, Is there a way to merge cards or something like that? All I've seen for trash cards is to just sell them.

 

[Bryanis]

Simply put, it's the xp foder card. it's only use is to gave lot of xp to other card.