In its current state (since season 22) two tailed fox only really benefits from one kind of surge mod. (Arc, since that is the active element when the rockets impact). It also only works with arc loader (mostly) and void reserves (mostly). Before that for like half of season 21 it worked at least with all of the surge mods. These changes also went without any mention in the patch notes. Since it is meant as a rocket launcher synergizing with all light subclasses, with it having their verbs, I think it should be updated/reverted to work with any of the elemental weapon mods, especially/at least surge mods. PS: I have personally tested all 3 surge mods on it this season. Arc is the only one getting close to the 22% it should be.