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The Silver Seed adds many new and incredibly powerful weapons to the game world, but you will need to solve each puzzle to get them.

After you've died for the first time with the expansion installed Karnax will give you the Amulet of Balance; double-click this when on or near any Serpent Gate. The first time you go through you will see a lengthy teleportation sequence, but after the first time you'll skip this scene. Upon your arrival you will discover that you have traveled back in time some thousands of years to the time of the great War of Imbalance, and are now within the grounds of DeathWatch Keep, an Order stronghold keeping watch over the forces of Chaos.

Note that it takes a whole week for the Amulet of Balance to recharge, so if you want to pop in and grab an item or two before continuing your quest you'll need to repeatedly sleep in order to leave once more. Once you've planted the Silver Seed the Amulet no longer needs charging and can be used at will.