"This mine creates spectral ore when you feed unupgraded ore into its cauldron. It will mimic the ore it's fed and grant a bonus."
The Witch's Cauldron is an Exotic-tier dropper that was released in the Halloween 2019 event.
The Witch's Cauldron has a very unique effect in which ore can be input into the cauldron at the back. In return, the Witch's Cauldron produces 2 standard size (1^3 studs) purple ore which retains the tags, upgrade count, effects, and the value of the original ore multiplied by x15. The only exception to this rule is the Ore Tracker tag as while it does carry over, it does not properly update.
As for drawbacks, this item has several. The Cauldron requires some form of elevation; a Large Conveyor Ramp works well. In addition, the Witch's Cauldron does not accept ores from Hades' Fang or The Abomination and The Daegelart. Lastly, it can only be used once no matter what.
The ability to produce ore at a standard size is a give-or-take situation, it's up to the user if they want this or not.