You can upgrade the brobot’s rank with cards + crystals, and the brobot’s level with crystals or credits.
Upgrade Rank
- Rank C to rank B, requires 20 cards and 50 crystals.
- Rank B to rank A, requires 50 cards and 100 crystals.
- Rank A to rank S, requires 120 cards and 200 crystals.
Upgrade Levels
There is an increasing cost of crystals for each level starting at 20 for Level 1 to 2, and ending on 26 700 for level 99 to 100. Here is a complete listings on Reddit.
These are the accumulated costs:
- 1 to 10: 1 320 credits
- 1 to 20: 8 440 credits
- 1 to 30: 23 540 credits
- 1 to 40: 46 940 credits
- 1 to 50: 78 740 credits
- 1 to 60: 121 240 credits
- 1 to 70: 180 640 credits
- 1 to 80: 269 540 credits
- 1 to 90: 408 240 credits
- 1 to 100: 627 640 credits
You should absolutely try to rank many brobots to S – it is well worth it for most brobots. Most of them have special abilities, which are handy at one time or another.
However, reaching rank S, consider saving credits for other things rather than continue to increase level. Of course the will be an increase in performance, but the final 20 levels are very expensive. The first 80 levels will cost you under 270 000 credits. The final 20 levels will cost over 350 000 credits…