Each season lasts approximately a year, and ends with the season's World Championship (WC). The World Championship usually occurs around early October (the Season 2 WC started on October 4, 2012 and the season 3 WC started on September 15, 2013). The Season 2 WC had 12 teams participating; the Season 3 WC had 14 teams participating.
Each competitive region of League of Legends were given a certain number of teams they could send to the WC. For the Season 3 WC the distribution was as follows:
- Southeast Asia: 1 team
- Europe: 3 teams
- Taiwan / Hong Kong / Macau: 1 team
- North America: 3 teams
- South Korea: 3 teams
- Mainland China: 2 teams
- International Wildcard*: 1 team
Two notes on this: The International Wildcard was a tournament between regions that did not yet have a large competitive scene (Brazil, Oceania, Lithuania, and Turkey) to send one team to the WC.
In addition, South Korea earned an extra spot up from their originally intended 2 spots by winning the All-Stars challenge in Shanghai, a tournament where each region sent 5 of their best players to compete in an tournament.
Each region selected their teams individually by the governing body of the competitive scene in that region. The structure of how each region decided to select which teams went to the WC is different.
North America and Europe
The North American League of Legends competitive scene is ran by Riot Games. It consists of two leagues: the League Championship Series (LCS) and the North American Challenger Series (NACS).
The LCS is a competition between 10 teams as of 2015 (formerly 8). It consists of two splits, each which in turn consist of a Regular Season and the Playoffs. Here is the basic structure of a single season of the LCS, using North America 2014 as an example:
- Spring Split:
- Spring Promotion (December 6, 2013 - December 22, 2013)
- Spring Round Robin (January 17, 2014 - April 6, 2014)
- Spring Playoffs (April 18, 2014 - April 20, 2014)
- Summer Split:
- Summer Promotion
- Summer Round Robin
- Summer Playoffs
The Promotion Series decides which teams play in the Round Robin. The top 4 or 5 teams of the previous split stay in the Round Robin no matter what. The bottom 3 or 4 teams, decided by the Playoffs of the previous split, play against the top 3 or 4 teams of the NACS. The winning teams are seeded into the LCS Round Robin, whereas the losing teams are seeded into the NACS.
The Round Robin lasts approximately 11 weeks. Across these 11 weeks, each of the 8 teams will play 4 matches against each of the other teams- 28 matches for each team. The record of wins to losses for each team is recorded. At the end of the 11 weeks, the teams are ranked according to their win-loss record.
The top 6 teams participate in the Playoffs. The top 2 teams (based on the win-loss record) are given a bye to the semifinals. Here's an example of the playoff bracket layout.
The European LCS is ran the same way.
The top 3 teams of the Summer Playoffs are then sent to the WC.