Boardgamegeek https://boardgamegeek.com/boardgameexpansion/143827/descent-journeys-dark-second-edition-trollfens
English - The Trollfens is an expansion for Descent: Journeys in the Dark (Second Edition) that introduces new heroes, monsters, classes, quests, and more. Heroes can discover and investigate secret rooms and rumors while the overlord spreads infection and brings a powerful new lieutenant into play: the massive troll Bol'Goreth!
Ludovox http://ludovox.fr/jeu-de-societe/descent-v2-les-marais-du-troll-6824/
French - Un jeu de Adam Sadler, Corey Konieczka, Daniel Clark.