Essentials Rust Monster

[Plane Sailing]

I've never understood the need to mechanically retcon rust monsters in the first place. If they destroy equipment, the DM can just make additional treasure available at later points in the adventure as they see fit (if it is needed to balance an adventure properly, for instance).

 

[Shin Okada]

Thing is:

you can use it, but you need special reagents for uncomon and rares...

Just for curiosity, is that rule actually shown already?