Mob Gems

Players capture a mob with a diamond and receive a gem that holds that mob's power. The Capture enchantment traps mobs in the same way, so a gem can be made from a creature met in the world without a separate hunt. Bracelets let the wearer take on abilities drawn from a mob, some helpful and some harmful, and Golden Bracelets go further by granting effects that copy the mob's behavior.

Gem Cages use mob gems to create area effects around a position, giving a placed cage a continuing influence on nearby space. Other gem effects cover igniting entities so they explode, raising maximum health, creating a forcefield that blocks projectiles, and increasing gravity. The mod is published for Fabric only, for 1.16.5, and requires Fabric API to run. Both client and server need it, and it is released under the GNU Lesser General Public License v3.0 only, so the source is open.