I would love to see additional obs in game.
We currently have demon fire, poison gas, grease and water.
I would like to see an acid orb, and maybe a cold based orb, the cold could use black ice as an ingredient.
You could also make some sort of corruption orb using demon blood, it might add corruption, or status effects like cripple or some kind of mutation.
The Cold orb could slow, acid might deal different damage to objects vs people, and fire could be adjusted to affect different things different. It would also allow for more combinations of items.
Sonic orb could damage and deafen, it could deal more damage vs those rock/crystal dog like things.
You could also add a knock out orb that is gas but that puts people to sleep instead of killing that could be used for help capturing thralls, or sneaking by people
With Demon fire being more explosive maybe a true fire orb is needed too like alchemist fire. The combo with the grease makes it more like an aoe or napalm that sticks to people
I also think orbs should be able to be combined with more than just themselves. For example I spent a lot of time throwing grease orbs and trying to light them on fire with my torch or flaming arrow without realizing i could only use a demon fire orb to do it.
I am sure some people can come up with more ideas.
Edit: just thought of something else, Poisons, the cauldron could be used to make poisons that could be applied to weapons. The set shrine could also make a special set poison, instead of just set arrows but a poison that could be put on any weapon unique to set