RIot the damage to champs nerf on GP Barrels is not the nerf that he needs

I get that you want to nerf him a bit but the issue is not the damage on his barrels overall, it is that he has no mana cost on his barrels allowing him to use them indefinitely in laning with no worries of having no orange to save him when getting ganked or a trade happens. In other words no clearly shown time periods of vulnerability while laning. Add on the massive amount of zoning from these barrels and it should be clear why it is a problem.

TL;DR limit his early game zoning and safe laning in order to allow him to stay a late game powerhouse.