"Well, I don't want to face a dungeon monster myself, but they wouldn't harm a cute girl like you. I'll let you keep the Buzz Rod since you've been such a good model. Bye bye!"

"Fuck you!"

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Derros are dungeon-dwelling dwarves who have given in to their amoral perversions. Working in Netherworld labs they have become more gnome-like.

Derros like to try out various restraint devices on captives. These items sometimes have locking mechanisms and sometimes they have to be cut away. The quality also is variable.

The devices are charged with mana by the victim's arousal. This will increase the enchantment level of the item, for example turning a one-use item unbreakable.

Sooner or later a captive will end up in a restraint that is both indestructible and without a working unlocking mechanism. That captive is now useless for further research, and is typically left in a dungeon corridor to be found by adventurers or the Dungeon Master's minions. The Derros consider this a great way to showcase their craft to the world.