Unable to find a challenge for this, but the goal is to complete 5 series'. The series' do not have to be started and finished if you already have series' ongoing but the plan is to complete 5 of them by the end of the year. My rule states that each series has to have at least 3 books in it to count (no duel book series') but of course it can be adapted to anyone's preferences if you just wanted a challenge to connect with even if its not exactly the same as your goals! :)