Complex sentence: In 2014, Sun "XiaoXiao" Yalong retired and on December 2014, Lee "KaKAO" Byung-kwon and Song "RooKie" Eui-jin joined as new players of Invictus Gaming.
Split into simpler sentences: In 2014, Sun "XiaoXiao" Yalong retired. In December 2014, Lee "KaKAO" Byung-kwon and Song "RooKie" Eui-jin joined as new players of Invictus Gaming.