Is it possible to cheat in DragonSoul?
Chating is possible, mostly through automation by use of bots and other automated scripts that play the game for you. There are also some minor hacks, hacked .apk clients and minor exploits here and there. However, there is NO way to get unlimited gold, diamonds, VIP, stamina, hero health and so on, since this data is on the game server and therefore is not hackable in any way whatsoever.
Is it legal and will I get banned for using cheats?
Cheating in any kind of game, the use of hacks for your personal account and bots to automatically farm is completely legal everywhere in the world. The worst thing that can potentially happen is your account getting banned, since the developers (PerBlue) have the right to ban any account for any reason whatsoever. However, bans are unheard of in this game at this point.