Opponents can't choose this card when resolving an effect. Effects that don't choose, such as ones that hit everything, still affect it.
Official rule 8.15 (Comprehensive Rules 2.2.0). This keyword appears on 58 cards: 56 Character, 2 Location. By ink: 29 Sapphire, 27 Emerald, 2 Steel, 1 Amethyst, 1 Amber.