
PSA Mandate on PBE E Interaction
So the new Imperial Mandate applies a 6% damage amp on immobilizations for 4s. What the item doesn't say is that reapplying this effect both refreshes the duration and applies another stack. Because Swain E technically involves 2 separate immobilization effects (Root+Pull), this means that it's functionally a 12% damage amp off of your E.
I suspect that if this interaction isn't changed, Mandate will be an extremely powerful item on Swain, at least for his support builds.