Hello there,

as I understand it, using a 2* hero gives you 2 % of possibility to increase the special ability.

Using ten 2* heroes leads to possibility of 20 %.

I suggest that using more heroes increases the possibility more than simply adding it up.

For example:

1x 2* => 2 %

2x 2* => 4 %

3x 2* => 7 %

4x 2* => 9 %

5x 2* => 12 %

6x 2* => 14 %

7x 2* => 17 %

8x 2* => 19 %

9x 2* => 23 %

10x 2* => 25 %

Of course these numbers are just an idea and would also apply for all other heroes (1*, 2*, …)

Best regards,

Vet