At first I thought the format was
Groups - 100% identical to what we saw the first 3 days, each team faces the other twice
Elimination- The team with the least amount of wins vs the team with the most after groups for example
TSM vs G2 P1 vs UOL C9 vs FNC - no team are eliminated from groups best in the "Knockout" stage teams face their opponents until each teams' region are eliminated. So if TSM beats G2, P1 beats UOL, but FNC beats C9; Fnatic will have to face both TSM and P1 and vice versa.
Instead we got a format that isn't the best when deciding who actually won, NA won 12 out of 18 games but EU could win the Finals and be the winners of RR, not a fan of 50/50 in tournaments.