In the game this is kind of the central currency.
Things you buy for crystals:
- plane cards and brobot cards in Contraband Shop
- evolve higher rank of planes and brobots (when you have collected enough cards)
- level up 10 levels of planes at the time
- use “Extra” when developing devices in Black Box (probability of a better item is improved)
- Elite Containers
- Planes can in most cases be bought either from crystals or credits.
Ways to earn crystals:
- buy VIP – this will give you 300 crystals, and then 40 crystals per day for 30 days
- buy crystals in Crystals Shop
- heroic missions will earn you crystals
- Daily Bonus will give you crystals on day 2, 6, 9, 13, 16, 20, 23 and 27.
- In Broshop, each reset will give you on purchase of 12 or 20 crystals.
- Each of the 5 levels in Assault will reward you some crystals. One entire run in Assault will give you 131 crystals.
- Some Daily and Progress Quests give you crystals