I know I'm a little late, but I hope Vechs sees this: You can already do this. With custom potions, I mean. Here, just watch this video: (Skip to 2:13 if you're not in the mood for humor, or to 4:54 for the exact bit I'm talking about)Quote from Vechs
I've already asked for milk in glass bottles. If they're added, I'll make all witches drop milk bottles.
Milk buckets felt OP to me.
Basically, you can make custom potions that clear all negative effects, "magic milk", as it were. Not 100% sure, but from what I understand it overrides the old effects with new ones that last for such a short time that you don't notice them. I imagine this knowledge would be useful to mapmakers. Also, that guy deserves more views, check out some of his other content, he's pretty entertaining.
By the way, Vechs' new test world video is terrifying.