A heavy graviton beam was mentioned as a possible weapon against the Borg in Best of Both Worlds (got rejected), but was actually used in Voyager to open portals into fluidic space.

Since we now have that beam as part of the MACO set against tehBorg, wouldn't it be fun if there was a slight and undocumented chance (not intended by Starfleet) to open a portal to fluidic space and spawn an Undine ship?
The Undine would then start fighting the Borg ships until Borg are destroyed or fired upon by players and turn on them or get destroyed itself, of course.

This would work a bit like the Triolic Pattern Enhancer on the ground summoning TOS NPCs, tribbles and sometimes Devidians.

http://en.memory-alpha.org/wiki/Graviton_beam

I would have thought things like spacial anonamolies and black holes would be generated by it.. anything that has a deflector involvement,

As for introducing the undine element, not that fussed either way , like triolic i never see the 3piece maco set being used.. though with the death of the 2piece/3piece zombie combo... who knows?