Gold is very hard to get and when doing things cost gold, it makes the game very hard for me. I suggest remove gold and upgrading cost/fusing cost should be free.
On the same note, I think since pulling rate is so slow, free gem monthly should be given out so people can pull many times each month. This way, people will have more chance of getting their 5* able heroes and able to limit break their team to 40 faster.
This also helps combat p2w; since now if gold is removed and gem are given out, the p2w has less advantage and the game will become more balance.
/s