The Forge is the very first of the seven monthly DLC releases that are available for free to all holders of the Shadow of the Tomb Raider Season Pass, and will provide players with lots and lots of new content, ranging from simple cosmetics, all the way to brand new narrative content.
Starting with The Forge's new challenge tombs, players who complete them will receive the new Grenadier skill for Lara, a new Brocken outfit, and the Umbrage 3-80 firearm, so as to cover all the relevant areas of content for Shadow of the Tomb Raider.
Of course, the main draw of The Forge will for most of the players be the introduction of a brand new cooperative mode of play to Shadow of the Tomb Raider, and the vast majority of content which the expansion adds will be playable both in singleplayer and in cooperative multiplayer.
It is also worth noting that The Forge will introduce Score Attack and Time Attack modes to the game, though we don't know yet to what extent will these be implemented. Set to release on 13th of November, The Forge is going to cost $4.99. That said, be sure to check out our Shadow of the Tomb Raider Mod Page for even more free content.