ok lets say you want to use frost nova.



Then the best way is to do this:


Toon 1: noting bound

Toon 2: create 2 buttons and bind one as "A" and then oter as "Ctrl + A"
Toon 3: create 2 buttons and bind one as "A" and then oter as "Shift + A"

and remember to not have "Ctrl" or "Shift" in the do not pass section