We tend to get specials like this, but they're available for only a limited period of time, and they're not included in the Miracle ticket pool. In other words, they're money sinks for whales. These limited characters often feature combinations of abilities that are uncommon in that element, such as Dark Amaterasu's class B debuff for Dark, or Light Nike's strong ATK buffing / double Full Burst capability for Light, making them particularly valuable for alternative builds.