Rune of Sin
This jagged glyph, one of the Thassilonian runes of sin, reacts to magic of a particular school (there's no rune for divination, as it was considered lesser within sin magic). When you Cast a Spell of the school matching the sin, you gain resistance 5 to damage from spells until the start of your next turn. This resistance is increased to 7 against spells of the matching school. This tattoo has the school trait matching the rune: abjuration for envy, necromancy for gluttony, transmutation for greed, enchantment for lust, illusion for pride, conjuration for sloth, and evocation for wrath.
Traits
This magic comes from the arcane tradition, which is built on logic and rationality. Anything with this trait is magical. A creature with this trait is primarily constituted of or has a strong connection to arcane magic.
A character can invest only 10 magical items that have the invested trait. None of the magical effects of the item apply if the character hasn't invested it, nor can it be activated, though the character still gains any normal benefits from wearing the physical item (like a hat keeping rain off their head).
A tattoo is a type of item that is drawn or cut into a creature's skin and usually takes the form of images or symbols.