The 2021 Mid-Season Invitational (MSI 2021) is held between the first and second splits of all regions. The champions of each competitive region compete for the MSI title. The tournament will be divided into 3 stages. Stage 1, 12 teams will be divided into 3 groups of 4 teams and will play in a double round robin. Top 2 of each group will advance to Stage 2 where all 6 teams play in a double round robin. Top 4 teams will advance to Stage 3 where they will play in a single elimination bracket.