You can directly change blue/purple crystal value you just have to make sure 2 values are the same at the same time.
One of the 2 values is encrypted with xor tho here's what it look like
There's no way to make it free with GG you might change it to make it look like it's free at most but that's it. There's another way to get the hero you want tho
You just have to group search number of materials you have in your bag
e.g. on my screenshot I have 999 materials 5 times in a row so I search 999;999;999;999;999:17
Once you have the right value you just need to go to the value's address scroll down a little and you'll have the id for every materials you have in your bag. You just need to fidle a little with them and you'll easily figure out how id work. (Materials id range between 101 to 719 and You need to restart the game to summon them)
Chest drop rate can be changed 0.259% is just 259D and 4.900% is simply 4900D
So with a group search you can find them and change them.
For weapon you should just upgrade weapon to find level once you've found the level value go to the address and change id and level
When you know weapon id you can just do group search to make it faster.
(2505, 2511, 2517, 2523, 2529 are the id for best weapons)
Fell free to ask if you didn't understand something but if you don't know how to goto address or what Xor or group search is then there is a great guide in GG just go and read help in GG, there are also guides in this forum if needed.