The censer (or thurible) is a gold container that can burn potions to release and spread that effect in a certain range. It is crafted similar to a lantern but with gold nuggets, a bar, and a fire charge for fuel. When a potion is burnt in the censer it will become empty and flame and smoke will come out of the censer (maybe there could be an animation where it opens). The potion effect will then be spread around the censer for a while as it is burnt.

I already posted this on the minecraft suggestions and it is on the feedback site now:

https://feedback.minecraft.net/hc/en-us/community/posts/35242727196813-Censers-that-can-be-used-to-spread-potion-effects