Talk:Challenge Booster Pack/@comment-24549318-20160715023114/@comment-28738889-20160726033912

It means that they were also found as rewards in specific challenge battles. Darkseid Prime was a reward for completing c specific battle in BNMM's challenge, and ABB was a reward for completing a specific battle during RLHJ's challenge. The same thing happens now, only with silver characters instead.