So i've been on here for a while now, but never posted because i didn't think i could provide input.
I'm a long-time fan of Shadowrun since '07, back in middle school coming across forum boards and RP fansites.
I've always enjoyed the idea of the Horrors and Invae and other Extraplanar entities, which creates a theory on how manacycles work on a galactic scale.
What if Horrors and Shadow spirits and Invae live on the astral planes(or even physical areas) of other planets, and use our connection to mana as a sort of long-way astral travel from their place to ours? Once enough mana flows in for them to construct capable enough astral forms from, they enter our world and wreak their havoc and whatnot. The planet(s) of the Horrors could be in other parts of the Milky Way, or even just in nearby galaxies can be considered plausible.
This could also give rise to the idea of magic soon being able to be worked easily in places other than Earth as it grows stronger in our solar system, as long as appropriate mana fields and generated to draw power from.
Any ideas on its feasibility? Any detractors?