Sorceress - Stormweaver Bug - Force of Will Node

The Force of Will node states, "20% increased Effect of Arcane Surge on you per ten percent missing Mana."

However, missing mana has no effect on mana regeneration. I don't think it affects cast speed either, but I'm not sure. This could be an interaction with another keystone or notable, I have both Mind over Matter, Eldritch Battery, and Wildsurge Incantation. Unfortunately, I'm not able to test if it without any of them as I'm in hardcore and not willing to risk it.

Thanks