Rust Monster
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The Hook
A druid is raising and training Rust Monsters as assault beasts against his foe the nearby dwarfs. He lures in and feeds greenhorn adventures to his pets in order to build their numbers and strength.
Inspiration to Draw on
Rust Monsters are subterranean dwellers usually and these things tend to be a nasty little surprise to adventurers that carry precious metals, metal weapons, or any sort of metal armor. Basically metal in general… The reason why is because these things eat metal. Can if you look at that cute mug in the picture over there, it is not breaking up forged steal with its chompers. rust Monsters do what their name sorta implies, they turn the metal that their antennae touch into rust. They do this until the matter is easily breakable or just dust. With metal being their source of food, these beast can understandably become agitated in the presence of metal as their hunger for it is seemingly unending.
Traditionally these monsters have been found in dungeons of nefarious wizards looking to protect their tower or roaming the Underdark with some of their nasty beast friends that don’t care for metal at all, they just love the squishy bits on adventurers. But, they have been known to stumble into many unexpected situations much to the chagrin of delving and meddling adventurers.
Now some things to think about. Much like a Purple Worm will obviously catch gem’s between its plates of armor, you will want to think of the biological things that a Rust Monster accomplishes, especially for its ecosystem. What would their leavings be used for? Does it have Alchemical properties? Is it combustable? Also, what is causing the oxidation in the metal? Is it a magical effect and if so when does the magic where of? What are some real uses that people might want the rust antennae?
Check out D&D Beyond or your always near to hand copy of Monster Manual for more history on the Rust Monster and remember to have fun with it!
Fair Use
Monster of the Week is a series we put together as a way to help DM’s generate ideas for adventures or campaigns. Please feel free to use these ideas freely. If you do use these ideas for published content, we just ask that you reference DM’s Table and reference https://www.dmstable.com/.