A more powerful form of a Talisman (and Periaptery).
There are many Occult Models to serve as an example.
d20 [specific] Crafting Requirements: Occult Aptitude 1 OR 3 [Occult] Allotted Essence.
These types of trinkets can contain no more power than granting a +3 on Spell Attack or Increasing a Spell Save DC by 3; it can impact spell initiative or effective level by no more than 3. Conversely, it can grant no more than +3 on checks to resist (base Ability or specific Save) effects, or +3 on Skill/Lore checks. It can augment a Mana Pool no more than 10.