Screamer Engine

The world of Pandom is the wreckage of an apocalypse that took a millennia to play out. The Raxus have not forgotten the world that was but they no longer have the skill or resources to create as their ancestors once did. The Raxus of the present maintain old technomagical engines and technology to ease the harshness of everyday survival on the world.
The fauna of Pandom include several species of aggressive creatures who actively hunt magical energy, from the casting of spells to ancient enchantments and the technomagical wonders of ancient Pandom. Among these creatures are the large Giganfleer, the vicious Glowhounds and the frustratingly invasive Dust Moths. Against these threats the users of technomagic on Pandom have few options, they can attempt to shield the power source of the technology, they can attempt to be ready to defend it against the hungry creatures or they can change the methodology of the power generation entirely.
A Screamer Engine is an example of the last option, a heavily jury rigged technology on the world of Pandom that uses a sentient individual as its primary power supply using blood magic. The unfortunate soul is bound inside of a special container that has been hooked up to the engine, impaled on five hollow spikes so that their blood can slowly drain into a rune scribed repository that converts the life energy and transmits it into whatever device needs to be powered. Some of the blood magic is looped back into the restraints, healing and maintaining the sentient power source. The engine can modulate the draw and unless the blood magic is the entirety of the source, an individual can be kept alive in the engine almost indefinitely with old age being theoretically being the cause of death. More often however the individual dies due to an overdraw event or is put out of their misery. An individual can be removed from the engine without killing them if needed.
In some cases this process powers an engine entirely but in most cases it is used just to muddle the arcane signature of the engine, making it far less likely that creatures who hunt magic will be attracted to them. Examples of Screamer Engines being used can be found on Venn Driftersand Crawlers as well as helping power smaller settlements. Larger cities tend not to use them as they often have defenses that can repel any hungry creatures.
The less scrupulous out there kidnap others, using them until they are drained and dumping them. Others find ways to consider it a sacrifice for the greater good. Some will spread load the burden, as the engine does not kill on its own a particularly egalitarian crew or settlement might have a lottery that assigns people to the engine for a period of time.