Add a cooldown reduction mechanism for Light Infusion. Such mechanism is based on the following:
Every time Turalyon gains 5 levels (starting at level 1), the cooldown for Light Infusion is permanently reduced
by n seconds.
In terms of lists:
- heroLevel = {1, 5, 10, 15, 20}
- cooldown = {20, 19, 18, 17, 16}