The legend of fusion says that some ancestrals may have had the power to fuse with one another. This technique supposedly doubled a persons PL by combining both beings into one. The two beings would then unfuse after 1 day. Once fused the new being had traits resembleing both beings and had all the knowledge of both. This was one of the main techniques used in the great war by those opposed to the use of the Relics of Power.
Recent info revealed about this legend: