Countermagical Handcuffs (cuffs)

Colloquially called ‘mage cuffs,’ these steel handcuffs let law enforcement agencies, criminal groups, rebels, conspirators, and others restrain prisoners who might otherwise use magic to slip away. When they were first mass produced in 517 aov, incarceration reformists breathed collective sighs of relief as the need for stringent and often cruel countermagical security features was greatly reduced. Engraved runes and mystical geometries create planar conduits to Urim, selected for its enhancement of the metaphysical concept of barriers. Urim’s planar energies pour into the steel, reinforcing it under certain conditions.

Normally, these act as nothing more than regular manacles. If placed upon you willingly or while at 0 hit points, a soft and aureate light begins to limn the handcuffs, signifying that they have been magically reinforced until the next time they are removed. While so magically reinforced, all DCs associated with circumventing the manacles increase to 30.

Additionally, whenever you use any non-permanent magical effects (including but not limited to spells, charming gazes, frightening auras, invisibility, shapechanging, telepathy, teleportation, the Incorporeal Movement trait, legendary actions, or lair actions), you take 4d6 psychic damage and must make a Constitution saving throw or else the magic you attempted fails to happen. Similar to concentration, the DC is 10 or half the damage you take, whichever is higher.

If someone attempts to break the cuffs, you take damage as if you tried to use magic. The cuffs have 30 hit points, and either resistance or immunity to most types of damage. 

When damage from the cuffs reduce you to 0 hit points you stabilize and they deal no additional damage until you have 1 hit point or more. The cuffs, however, only have three charges each hour, so a very committed prisoner might manage to power through an escape attempt.

For the most magically powerful foes, greater bindings that use similar principles might be employed. The uncommon ‘magebinding jacket’ deals 10d6 psychic damage and also keep you restrained. It too only has three charges per hour, but as yet no prisoner has ever been known to fight past more than two. Courtesy of Urim’s aureate energy, the jacket has 50 hit points.