Custom Ladder Or Tournament; it's a framework where you string together some Warlight APIs (Validate Token, Create Game, Query Game mainly) to create your own ladder/league/tournament.
You can find some boilerplate for that at: https://github.com/FizzerWL/CLOT
Better boilerplate in some forked projects: https://github.com/deadman1
And the Warlight AI: https://github.com/FizzerWL/WarLight.AI
But Warlight itself isn't open-source.