The Rift is an interdimensional portal which resides deep below the castle of Daemonheim. Little is known about the history of the Rift, however the Mahjarrat Bilrach spent a very long time searching for it. He, along with Lucien's daughter, Moia, entered the Rift where they encountered Zamorak.
According to Bilrach, the Rift is a place where the barrier between the realms is weakened. He wants to use this weakened area to allow Zamorak to return to Gielinor from the realm he currently resides in. Bilrach also uses the Rift's weak barriers to unleash many fierce monsters, like the stalkers, behemoths and the Kal'Gerion demons, upon Gielinor. He uses those monsters to guard the dungeons he creates while digging towards the rift.
The strange power event which occurred on 23 January 2010 was previously believed to be caused by the Rift. However, upon completion of the quest Ritual of the Mahjarrat, a conversation with Ali the Wise reveals that the event is usually caused by the death of a Mahjarrat while under the influences of perfect planetary alignment, the same concept used in the rejuvenation ritual. Despite this, it was confirmed that the strange power happened when Bilrach sacrificed the last surviving Chelon-Mah.
The strange power also attracted the Fremennik's attention. They went to Daemonheim and are currently raiding the dungeons Bilrach created, trying to find the exact source of the power.
It seems likely that the many strange resources found in Daemonheim originated in other dimensions, and came through the Rift.
The Rift is also believed to cause various rooms below Daemonheim to relocate themselves to another location, since Bilrach states in his journal that the rooms he digs collapse and reappear elsewhere. This causes much trouble for both Bilrach and the Fremenniks seeking to reach the bottom of Daemonheim.
According to the Fremennik Saga Nadir, in year 168 of the Fifth Age, Bilrach was on floor 60 and was digging toward floor 61.
A Q&A at RuneFest stated that floor 61 would be released soon, also hinting that it would contain someone that had a name starting with the letter "Z". This is confirmed to have been Zamorak, who buried himself beneath Daemonheim when banished by Guthix, 'not quite in the world, but close.'
- ^ Bilrach, Mysterious chronicle (part 24), RuneScape. "I, Bilrach, will find this Rift, where the barrier between realms thins."
- ^ Bilrach, Mysterious chronicle (part 20), RuneScape. "Not only am I able to draw power from the portals as I once did, but I've managed to enslave ever-more powerful and destructive beasts. The stalkers, the lumbering behemoths and the curiously noble Kal'Gerions are all creatures of my will now, defending my great work as if it were their own."
- ^ Ali the Wise, RuneScape. "Ah, you speak of the Daemonheim event. A case of the wrong Mahjarrat being in the wrong place at the wrong time... Such a waste of power."
- ^ Mod Crow. "Declare your allegiance!." 11 July 2013. Community Home Forums.