413.2a If the spell or ability specifies targets, it checks whether the targets are still legal. A target that’s removed from play, or from the zone designated by the spell or ability, is illegal. A target may also become illegal if its characteristics changed since the spell or ability was played or if an effect changed the text of the spell. If all targets are now illegal, the spell or ability is countered. If the spell or ability is not countered, it will resolve normally, affecting only the targets that are still legal. If a target is illegal, the spell or ability can’t perform any actions on it or make the target perform any actions. If the spell or ability needs to know information about one or more targets that are now illegal, it will use the illegal targets’ current or last known information.