Boardgamegeek https://boardgamegeek.com/boardgameexpansion/22361/descent-well-darkness
English - This is the first expansion for Descent. It includes new monsters (with figures), heroes, treasures, effects, scenarios, props, and more! It also features options for the Overlord player to customize his deck for each scenario. Deep in the bowels of the world, there lies a chasm that was sealed over a millennium ago. Within it lies a force of evil so great that, were it to be unleashed, it would plunge...
Ludovox https://ludovox.fr/jeu-de-societe/descent-le-puits-des-tenebres-extension-2132/
French - Un jeu de Kevin Wilson.