Costume as HA HoTM

Add a 5% costume probability to every HA10 S1->S1 retrain.

So, you will basically have 5% odds to old HoTM/s2/event heroes, and another 5% odds to get a costume for S1 hero (with hero) , which will benefit f2p/c2p greatly.

Any idea that can reduce SG profits will be ignored.