Night Vision potions should increase visible brightness for target creature only.
Visible brightness affects light spreading by increasing brightness of light sources (refactor light level to be stored as numbers, not enum). Visible brightness also affects blinding (if visible brightness is +2 then light level 8 would be enough to blind).
Visible brightness bonus and time should depend on potion size.
Night Vision potions should increase visible brightness for target creature only. Visible brightness affects light spreading by increasing brightness of light sources (refactor light level to be stored as numbers, not enum). Visible brightness also affects blinding (if visible brightness is +2 then light level 8 would be enough to blind). Visible brightness bonus and time should depend on potion size.