The Drogokishuun key is obtained after excavating the barricade and going down the staircase both ways within the Warforge. This can only be done by manually entering the Tunnel entrance in The crucible (first area) and selecting one of the 2 options (Left or Right), then going back and selecting the other option. This can't be done when first entering the Warforge and selecting to go to the tunnels directly. The key is used for opening the Forge Doors which is needed to complete the Into the Forge mystery.
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