Haagenti

Haagenti is the Pathfinder demon lord of Alchemy, Invention and Transformation ... and basically mad, steampunk science. Its titles are the "Whisper within" and the "Lord of transformation", and is credited as the creator (or the one that inspired) artifacts such as the first Philosopher Stone and other helpful objects. Due to this, he's perceived as more beneficial demon lord than others. This is, however, just a ruse, since with each of these gifts, new paths are open than may lead, over the years, entire civilizations to their rapid collapse and violent destruction through "unforeseeable" consequences. https://1d4chan.org/wiki/Tzeentch. Seriously, even one of the Pathfinder's creators has stated that, among the demons lords, Haagenti can be considerate a low key version of Tzeentch, albeit one that focuses exclusively on the domains of evil science.

While being a shapeshifter and not possessing a "true form", Haagenti presents himself ofter as a winged bull with golden horns - which takes from his goetia demon namesake - that can breath foul vapors which cause random mutations over those exposed, making them into "fleshwarped" creatures. Its divine realm in the abyss - the Cerebulim - is also described as a "clockwork labyrinth of endless laboratories", which sounds like a mixture of a forge world a the Planet of the Sorceres.

Due to his speciality in physical mutation and fleshwarping, Haagenti is patron not only to all alchemists and mad scientists, but also to many natural shapeshifting creatures (except werewolves, who already got https://1d4chan.org/wiki/Jezelda). He's also fond to the rare awakened constructs and other creature who "improve" themselves or others through the power of since.

A key aspect of Haagenti, which makes him different from your run of the mill demon lord, is that he tends to play the long game and employ subtle manipulations directed towards both followers and enemies alike. While other demons cults may aim to control and disrupt cities and societies, the Whisper Within aims are to corrupt the most brilliant thinkers and inventors to have them produce instruments of woe. For example, an alchemist could be inspired to invent a poison able to put down even an evil dragon, only to have this weapon used, 50 years down the line, to exterminate an entire line of good dragons in a war after them became wary of this weapon existence.