I would like to make a simple suggestion, but that will make the game much more interesting for players with a higher level (above 500, 700, 1000 etc).
When playing for many months and joining almost all the troops the game is getting repetitive and I'm sure many stop playing at this point.
After we have raised a troop until it is mystical there is no reason to join several repeated troops of the same troop. However, as it is, it is very discouraging to join new troops when you are at high level, we already have almost all the troops and one or the other missing or makes no difference, but even so the probability of it coming is very low, almost nonexistent, Which discourages further play.
My suggestion to solve this is quite simple: simply that when raising to mystic any troop or even those that are already mystical would have a counter of negative percentage so she does not leave again for each new troop as we have, that is, if I have 10 equal troops of the same troop she will have 10% change less to come when I open any chest. This percentage increases until reaching 100% (100 equal troops of the same unit), when then this troop will not come again when opening the chests.
This would be fantastic and would not change anything at all for most players, it would only change to the highest levels and it is precisely those who are probably wanting to stop playing and this would surely hold a lot of people in the game since it sets a limit for the repetition of troops.
I hope you appreciate my suggestion and that it can be used.