Champion's Trial is a two skin offer released for a limited time in December 2016. The skins in this offer could only be purchased with various packages of game items. They were not available for individual purchased. There may be limited opportunity to acquire these skins in the future.
Note: The Champion's Trial offer has been released multiple times after the initial 2017 debut. Additional limited time releases were in mid April 2019 and then in early December 2020. The prices and items included varied between releases. However, the included skins did remained the same.
Details of this offer can vary depending on location, platform or time.