When using the 200-crystal ‘Change new’ function on a hero’s passive skills, can it change the whole effect of the skill, or only the tier of the skill that is already there?
I ask because I tried to change a warrior’s passive from Magic Attack I and got Magic Attack III, and then I changed it again and got Magic Attack I again.
I don’t really want to spend any more gems unless I know there’s a chance to get a defensive passive.
You can get any passive skill you want if you’re willing to spend the gems. Just takes patience and/or luck.
Which skill pops up when you spend the 200 gems seems entirely random. It doesn’t seem like it is a lot harder, if any, to get the more powerful ones than the less powerful ones.
You will also never be offered a passive skill you already currently have in another slot.
The optimal time to start gambling on better passive skills is after your hero has reached 6 stars. You might unlock a skill for free that you could have paid crystals to unlock earlier. Further, if you have more passive skills unlocked, then the pool of remaining skills you don’t have is smaller. This will improve your odds of getting the skill(s) you want.
Yeah, I had just upgraded it to 6 stars.
So if it is definitely possible to change magic attack to something like magic defence or block, then i’ll keep investing.
Must have just been bad luck I got the same one twice in a row!
It can take a lot of attempts and therefore a lot of crystals. That’s especially true if you want to change every skill on every hero in your arena team to have the exact passive skills you want. 
Not saying that I know anyone who might do such a thing.
Not saying I don’t, either. 
