http://www.pcgamer.com/grim-dawn-expansion-ashes-of-malmouth-will-be-out-in-october/

Grim Dawn developer Crate Entertainment announced earlier this year that two new classes, the Inquisitor and the Necromancer, and a new Illusionist merchant would be coming to the game in a future DLC release. We haven't heard anything more about it since March, but today the studio released a new trailer revealing that the expansion, entitled Ashes of Malmouth, will be out next month. 

The expansion will add two new chapters to the game set in the Ugdenbog and fallen city of Malmouth, which appears to be somewhat more urban than the game's other locales, but still entirely grim. The new classes—Masteries, technically—will add more than 60 new abilities to the game, and of course there will be a pile of new items to collect, constellations to figure out, and bosses and mini-bosses to fight.