Rule 355.14.h.1

That player cannot choose to have fewer Targets than they have damage to split when choosing which Targets cease being Targets. Example: A player plays Alpha Strike, which reads in part “Choose a friendly unit. It deals damage equal to its Might split among enemy units at battlefields.” They target their 5 [M] unit and five 1 [M] enemy Recruits at battlefields. In reaction, their opponent plays Feral Strength targeting one of their recruits, and Frigid Touch targeting the 5 [M] unit. When Alpha Strike resolves, they have 3 damage to split, and must choose which targets cease being targets. They can’t choose for 4 of the units to cease being targets so that they can deal 3 to the 3 [M] recruit. They can only choose at most 2 of the targets to cease being targets.