Ty ! It answered my question ! :)
I have an other :s

in the shop we see :
250 orb + 50 free for 4.39€.

It means that we have 300 orb for 4.39 ? or 250 where 50 are free inside of these 250 ?

ty for your answer.

I saw some dungeon which had 2 trap upgrading at the same time. Do you know how to do that? It is a bug or hack? or it is normally possible?