Lee "Wolf" Jae-wan began his competitive career on December 21st, 2012 when he joined NaJin Shield as their new support. During this time, he went by the name "a Wolf". He played in his first major tournament at GIGABYTE StarsWar League Season 2 where his team failed to make it out of groups. Wolf came back to Korea to participate in his first OGN, OLYMPUS Champions Spring 2013. The team successfully made it past the group stage but got crushed 3-0 in the quarterfinals by the newly formed SK Telecom T1 2. Wolf left the team shortly after to join Chunnam Techno University. The team qualified for HOT6iX Champions Summer 2013 where they were swept in the quarterfinals again, this time by MVP Ozone. Wolf left CTU in October 2013 to join the newly reformed roster of SK Telecom T1 1. A few months later, the were renamed SK Telecom T1 S.
SKT played in the 2015 LoL KeSPA Cup where they lost 2-0 in the semifinals to Ever. This series was widely considered to be one of the greatest upsets in League history but also continued a streak of World Champions being eliminated early on in their first tournaments after Worlds. In March, SK Telecom attended IEM Katowice despite being only the sixth-place LCK team at the time. They brought substitute jungler Blank in place of bengi and swept through the tournament, winning the title after only seven games. After their international success, they returned to Korea and placed third in the regular season, earning themselves a spot in the playoffs. SKT won the playoffs, winning their third championship in a row and giving them a seed to the 2016 Mid-Season Invitational.