You can ask on the Tahm-Ken.ch Discord server if you want to add your community on the site (it doesn't need to be a Discord server). You must be admin of this community.
Find optimal composition for teamwork challenges in League with this open source tool.
Challenge Tracker (Website)
League of Legends Challenge Tracker & Leaderboards by DarkIntaqt.com
High Mastery (Discord)
A multi-region community focused on player improvement and the most efficient challenge farming in the world.
League Challenges (Discord)
Discord community to group up with players to complete challenges, discuss everything about league or chat.
Achievement Hunting (Discord)
A server for coordinated completion of League of Legends challenges.
Desafíos LoL ESP (Discord)
Servidor centrado en completar Desafíos de LoL en compañía centrado en apartados como Artista, Armonía pero expansible.