This is likely to be one of the last trophies you’ll get if you’re like me.
To upgrade potions you need golden amber which can be obtained from two sources, either chests (only normal chests contain this, not might, epic or guarded) or from chopping down trees which have a golden aura near their base.
I opened every single chest in the game and was still short about 40 golden amber so I would recommend keeping an eye out in forested areas throughout the game to save a grind at the end.
A good area I found for golden amber was in the gates of Tartaros. There’s a lot of trees if you circle the area and there’s a lot of chests as well so you can do both at the same time. There’s also 3 lieutenants you’ll need to kill for wings.