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.
UNDOCUMENTEDGetEventStatsForAccount
https://api.steampowered.com/IEconDOTA2_247040/GetEventStatsForAccount/v1/
UNDOCUMENTEDGetHeroes
https://api.steampowered.com/IEconDOTA2_247040/GetHeroes/v1/
UNDOCUMENTEDGetItemCreators
https://api.steampowered.com/IEconDOTA2_247040/GetItemCreators/v1/
UNDOCUMENTEDGetItemWorkshopPublishedFileIDs
https://api.steampowered.com/IEconDOTA2_247040/GetItemWorkshopPublishedFileIDs/v1/
UNDOCUMENTEDGetRarities
https://api.steampowered.com/IEconDOTA2_247040/GetRarities/v1/
UNDOCUMENTEDGetTournamentPrizePool
https://api.steampowered.com/IEconDOTA2_247040/GetTournamentPrizePool/v1/