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For both canon and legends what exactly was Mother Talzins powers do they have any link or connection with the light or dark side of the force? Does the Mortif family or the Father say anything with regards to her or her powers etc ?

In canon, Talzin's powers don't seem to be strictly linked to either aspect of the Force.

The sole reason she agreed to team up with Palpatine in the first place was to "mingle dark side abilities with Nightsister magicks":
https://i.imgur.com/0cBoLEW.jpg

Dark magics though.

Definitely seemed more dark then light.

The magics she used are different from anything else. That's why Talzin was able to do a lot of shit that not even Sidious could do.