I just got the red rank with my heroes, but I don’t know if I should invest the hero chips in them, because I have some that are not 6 stars yet, and also have the mods, in what I owed invest ?
Getting the first level of a red skill is often very helpful. Then, you can wait to get more levels in the red skill once they reach 6 stars.
For important characters, I would not spend their own hero chips to improve mods. Instead, give the mod to a pointless character who has excess hero chips. Use that character to improve the mod before giving it back to the original character (still costs 25 hero chips to receive the mod but that’s better than spending hundreds of hero chips of a character who really needs more hero chips).
Thank you very much, I think I will do it