However, there is also an alternative method that involves playing the recently released mobile companion gane, Uncharted fortune hunter. For completing a level in the requirement allowed moves you are awarded a key, which can be used to open chests. Now these chests come in periodically unless of course you spend coins to relieve them early. They are also random.
So, this is where the exploit comes in. All you have to do is search Uncharted Fortune Hunter Mod dedicated APK (I'm on my phone so it's hard to link stuff). There's a recent APK mod that gives unlimited money and orbs. All you have to do is get enough money and orbs to buy chests, and the money keeps stacking up so you can continuously buy them, and orbs would be used to unlock the in game easy mode cheat, thus allowing you to get keys fast.
I've gotten a total of 3125 relics, a bunch of boosters, and some of the exclusive rewards you get like hats and costumes. All of these can be transferred over to the multiplayer once you sync up. I've already unlocked all the characters.
It does have a stopping point as not all the levels are available yet, but you can always delete it and redo it all over again