This page is just a reference of all the known Steam APIs, I do not know how they work. Please do not email me with questions.
UNDOCUMENTEDGetParticipationDetails
https://api.steampowered.com/IDOTA2AutomatedTourney_2305270/GetParticipationDetails/v1/
UNDOCUMENTEDGetPlayerHistory
https://api.steampowered.com/IDOTA2AutomatedTourney_2305270/GetPlayerHistory/v1/
UNDOCUMENTEDGetTournamentDetails
https://api.steampowered.com/IDOTA2AutomatedTourney_2305270/GetTournamentDetails/v1/