Before you begin exploring a location, you can hire a friend as a helper. Press the Hire button to do this. You can only hire 1 friend at a time.
Every friend has a certain talent that will come in handy:
Accountant (coin icon): increases the amount of coins you earn by 10%
Keeper (blue icon): increases the amount of experience you earn by 10%
Joker (energy icon): reduces your energy consumption by 10%
Ranger (red star icon): increases your chance of finding collection items by 5%.
Each friend can only be hired once every 24 hours. However, you can hire them again for 5 rubies.