I'm gonna make the conjecture, since its obviously a blend, that HX3 might stand for H=Halo X=times 3=three flavors or elements. So of course menthol is one. I think the other two are Prime 15(almond) and Longhorn(cherry) because it has that cherry pipe tobacco thing. But if its actually 3 other Halo flavors with menthol added that make the blend, then the other element could be Midnight Apple or Torque56(apple and plum elements).
But I doubt Halo's gonna give us the recipe.

So....(scratches head)..Menthol, Prime 15 and one or two other juices.
It just bugs me that I can't pick this one apart as easily as the other Halo Juices.
Care to add anything Cinder Ella?