Onyx-Brass Farms have continued to develop quality products. Rust Monster Rennet is a type of un-aged cheese curdled with Onyx-Brass Rust Monster Milk. It is only rarely seen outside of Findle as a culinary product and aside from the Onyx-Brass Farms, It is produced only in very small quantities by the Findle Alchemeria. It's primary non-culinary use is as a paste which rapidly rusts items it touches.
Smearing a handful or throwing a small bottle of the rennet against an iron object will cause the object to rapidly rust over the course of one hour, dealing 1 damage to the item each minute.
The rennet can be combined to make onyx-brass farms rust monsters cheese, which is seen as a culinary delight for those with unflinching palettes.
Characters who consume the Rennet, or cheese made from the rennet must succeed on a DC 13 constitution save or be poisoned for 1d4 minutes and are immune to other consumed poison effects for 1d4 hours.
Hill dwarves and goblin-kin have advantage on the constitution save to avoid the initial poisoning.