X- factor question

spot

What does the number in the blue box in the right corner mean?
thanks

DFBB

If it shows zero, it means that it hasn’t been used before. If there’s a number next to it, it means that it’s been used and there will be a cost associated with re-equipping it. As an example, below is two sets of level 6 bg xfactors. As you can see, I have four level 6s that I’ve already used once. 

TimidDeuce

Does anyone have a chart of the cost of re-equipping X-Factor skills?

JTANDME

But why, aside from the usual GLU greed, does it need to cost gold to acquire them and then to equip it on different players? I get if you have multiple like Alex's example that it is not a huge thing but if I have one 6 and one 8 I shouldn't, in my finite mind, have to either buy the box and hope or spend 15 and up to re-equip. Just my two cents that mean nothing. 

spot

Thanks , that kinda sucks having to spend more gold every time you use it !