You strengthen cards by choosing a card to strengthen and then sacrificing up to eight cards which will be lost while the selected card is increased in level. Each sacrificed card adds XP value which is then applied to the target card. The XP value of the sacrificed card depends upon its rarity (# of stars), its level and its evolved generation. Strengthening is key to getting maximum value from cards and cards should be maxed out before evolving them. The ratio of value increase is constant for every card.

If X is the level 1 card strength for a given card, then the following ratios appear to hold (with a tiny margin of rounding error).

- Level 20: X * 1.57
- Level 40: X * 2.33
- Level 80: X * 3.45
- Level 160: X * 4.93

The amount of XP and number of coins required for each level up increases. Thus, strengthening from 1 to 20 is quite fast and requires ~160 XP while strengthening in the higher levels multiple sacrifice cards for a single level.

The amount of XP that a card will give when you sacrifice it, is its base XP (the amount it will give when it's level 1 - which depends on its rarity), plus 1/2 the XP you've put into that card. Thus if you've strengthened a 2-star card up to level 13 by sacrificing eight 1-star level 1 cards (80 XP), then that 2-star level 13 card can be sacrificed to give 80/2 + 14 = 54 XP to another card.

Base XP (to give) | |
---|---|

Rarity | XP |

1-star | 10 |

2-star | 14 |

3-star | 25 |

4-star | 40 |

Rounded to the nearest coin, the number of coins required to strengthen a card is $ coins=20*\sqrt{Level} $. This is the level of the card being strengthened, and is not dependent upon the card being sacrificed.

XP required to level | ||
---|---|---|

Level | XP | Formula |

2 | 4 | $ XP = \text{round} \left( \frac{1}{8} \cdot Lv^2 + 5 \cdot Lv - 7 \frac{1}{8} \right) $ |

3 | 9 | |

4 | 15 | |

5 | 21 | |

6 | 27 | |

7 | 34 | |

8 | 41 | |

9 | 48 | |

10 | 55 | |

11 | 63 | |

12 | 71 | |

13 | 79 | |

14 | 88 | $ XP = \text{round} \left( \frac{1}{2} \cdot Lv^2 - 5 \frac{1}{2} \cdot Lv + 67 \right) $ |

15 | 97 | |

16 | 107 | |

17 | 118 | |

18 | 130 | |

19 | 143 | |

20 | 157 | |

21 | 170 | $ XP = \text{round} \left( \frac{1}{4} \cdot Lv^2 + 4 \cdot Lv - 24 \frac{1}{8} \right) $ |

22 | 185 | |

23 | 200 | |

24 | 216 | |

25 | 232 | |

26 | 249 | |

27 | 266 | |

28 | 284 | |

29 | 302 | |

30 | 321 | |

31 | 340 | |

32 | 360 | |

33 | 380 | |

34 | 401 | |

35 | 422 | |

36 | 444 | |

37 | 466 | |

38 | 489 | |

39 | 512 | |

40 | 536 | |

41 | 560 | |

42 | 585 | |

43 | 610 | |

44 | 636 | |

45 | 662 | |

46 | 689 | |

47 | 716 | |

48 | 744 | |

49 | 772 | |

50 | 801 | |

51 | 830 | |

52 | 860 | |

53 | 890 | |

54 | 921 | |

55 | 952 | |

56 | 984 | |

57 | 1016 | |

58 | 1049 | |

59 | 1082 | |

60 | 1116 | |

61 | 1150 | |

62 | 1185 | |

63 | 1220 | |

64 | 1256 | |

65 | 1292 | |

66 | 1329 | |

67 | 1366 | |

68 | 1404 | |

69 | 1442 | |

70 | 1481 | |

71 | 1520 | |

72 | 1560 | |

73 | 1600 | |

74 | 1641 | |

75 | 1682 | |

76 | 1724 | |

77 | 1766 | |

78 | 1809 | |

79 | 1852 | |

80 | 1896 |