This feat belongs to an archetype.

Effects and magic items with this trait involve false sensory stimuli. Magic with the illusion trait creates false sensory stimuli. Sometimes illusions allow creatures a chance to disbelieve the spell, which lets the creature ignore the spell if it succeeds at doing so. This usually happens when a creature Seeks, Interacts, or otherwise spends actions to engage with the illusion, comparing the result of its Perception check (or another check or save the GM chooses) to the caster's spell DC. Mental illusions typically provide rules in the spell's description for disbelieving the effect (usually via a Will save).

If a creature engages with an illusion in a way that would prove it's not what it seems, the creature might know that an illusion is present, but it still can't ignore the illusion without successfully disbelieving it. Disbelieving a visual illusion makes it and those things it blocks seem hazy and indistinct, which might block vision enough to leave the other side concealed.

A mental effect can alter the target’s mind. It has no effect on an object or a mindless creature.

Actions with the spellshape trait tweak the properties of your spells. You must use a spellshape action directly before casting the spell you want to alter. If you use any action (including free actions and reactions) other than casting a spell directly after, you waste the benefits of the spellshape action. The benefit is also lost if your turn ends before you cast the spell. Any additional effects added by a spellshape action are part of the spell's effect, not of the spellshape action itself.