Jeong "Apdo" Sang-gil is known for being a high-Elo player on the Korean server, able to play top, jungle, mid, and AD carry, though he is primarily a mid laner. He is believed by many to be the second-best mid laner in the world after Faker, but by some to be overall a better player, since he is able to play four different roles and excel, while Faker is only able to play one. However, in contrast to Faker's countless tournament results, Apdo has never played in an offline tournament.
Initially, Apdo refused invitations to join pro teams because he earned more money by Elo-boosting, but eventually he attempted to play in the OGN Winter 2013-2014 Qualfier with a team called 양학하러왔습니다 (which would eventually rename to Team Dark and be disqualified from the tournament due to unsportsmanlike behavior). However, Apdo was still Elo-boosting, and a girl whose account he had boosted reported his activity to Riot; as a result, his main account was banned for 1,000 years as a penalty, and he was banned from participating in OGN. He would not be permitted to play in tournaments for the next two years.
Despite his permanent ban, Apdo continued to play on smurf accounts and reach Challenger with extremely high win percentages. He streamed for multiple streaming platforms, including Afreeca, Doyou TV, and YY TV. In September 2014, Apdo went to China to win 500,000 元 of the total 1,000,000 元 ($161,000 USD) prize pool for hitting rank 1 in Challenger, which he was able to accomplish in less than a month.
In October 2015, Apdo released a statement apologizing for his behavior in boosting accounts and trolling games and stating that all of his accounts would be banned. While he initially stated that he might plan to go pro in China, a later post suggested that he did not ever plan to play professionally.