Darkmine was the cavernous home to the Brotherhood of Ak'rei'an, prior to its ransacking by the Ussalry.
Darkmine is located in a tunnel off the long abandoned Onu-Ko Highway. From the entrance, the tunnel becomes a maze going down a mile beneath the highway. The tunnel is thick with traps and trick tunnels, and can only be navigated safely by Brotherhood members.
The cavern itself is two thirds as long as a football field, and is at its highest twelve stories tall. The tunnel enters from the far left, and the Brotherhood is settled in the far right, by a small river.
- The Temple: an open air construction. It consists of an eight-foot statue of Ak'rei'an carved of black stone, with its back to the entrance, cradling a Purple Lightstone. The statue looms over an alter of white stone.
- Conversion Chambers: a series of square, sealed rooms of stone where prospective members of the cult are tortured and brainwashed. It is partially underground and soundproofed, near the entrance.
- The Grand Master's Home: The Grand Master's Home is the residence of Larikon. It is a large structure of black rock, with two bathrooms and bedrooms, kitchen and dining room, a study and a library, among many other features.
- Barracks: Regular Brotherhood members sleep in a pair of barracks, Barracks One and Two.
- Miscellaneous: There is also an armory, ussal stable, smithy, slave tent (unused currently), field kitchen and food storage hut.
After the destruction of Blackrock Canyon by the Po-Koro Guard and Ga-Koro Marines, the survivors of the Brotherhood wandered the deserts for five years. That is until the hastily-elected Grand Master, Orkov the Savior, led them to the cavern of Darkmine. Unfortunately for the group, he died soon after.
A scholar by the name of Harsos was elected Grand Master soon afterword, and oversaw the construction and expansion of the fortress Upon his death three hundred years later, Darkmine was in its current state.
After Larikon's coup, its population was reduced to a skeleton crew. However, this small group managed to keep the base in shape, and ready for the flood of new recruits after the death of Makuta.
Darkmine was invaded by the Ussalry, the Brotherhood just barely escaping. After taking the caverns, they were converted into a fungi farm for Onu-Koro.
- Darkmine is the second fortress of the Brotherhood: the first, Blackrock, was destroyed in a relation by Ga- and Po- military forces.
- This is the second location called Darkmine. The first was run circa 2006/2007 in Terros Nui's earth region. Other bases of the pre-reboot Brotherhood were Bloodflow, in the fire region, Nuva Blackwave, floating in the water region and the mercenary training center Twisted Mind.