How to unlock new characters on the app
So when I first started playing the app game, there were only two playable characters: Tyrax and Mari. I'm a level 19 Tyrax now and I'm wondering, when/how do you unlock the other 4 characters? Do you have to purchase them with physical money? Do you have to buy the toys? Or can you unlock them in game? I'm curious because I haven't seen any clues as to how to get them. Thanks.