A creature with this trait is a summoner's eidolon. An action or spell with this trait can be performed by an eidolon only. An item with this trait can be used or worn by an eidolon only, and an eidolon can't use items that don't have this trait. (An eidolon can have up to two items invested.)

An invocation action allows a runesmith to surge power through their rune by uttering its true name. Invocation requires you to be able to speak clearly in a strong voice and requires that you be within 30 feet of the target rune or runes unless another ability changes this. These actions include the Invoke Rune action, which makes the rune’s invocation take place, then causes the rune to fade away. Using Invoke Rune normally allows you to invoke two runes, but other abilities that include the Invoke Rune action often change that number or the specific runes you can invoke.