You know how Witches love to chuck potions? Let's let them toss from inside a jar too! But it shouldn't be free...

I propose that, when a witch is in a containment jar, it could gain new functionality based on various Vanilla behavior of witches. When given a redstone pulse, a witch within a jar will attempt to throw a potion, spending 2% of an adjacent Source Jar if it is successful. It will always attempt to throw in potion priority order, and towards the closest target. If no targets exist, the witch jar will emit a witchy grumble sound and a handful of angry villager particles. If there isn't enough source, the particles will instead be smoke.
First, it will attempt to throw a potion of Healing towards any nearby illager captains (the ones with banners on their heads,) within 5 blocks. This will also target captains inside Containment Jars.
If there are no captains to fire at, it will instead fire a Slowness, Weakness, Poison, or Instant Harming potion at random towards the nearest player within 8 blocks.
I think this would be a fun way to allow Ars toggleable usage of vanilla witch-based healing fountains while still making it not a free source of healing.