Munchkin Impossible Spy Fly Question

[texasaggie]

We had a great game going and got sidetracked on what to do when the Spy Fly joined a combat.

In our case, there were already 2 monsters in combat against a munchkin with several items, including 3 guns (extra hands FTW!). Monster Mash was played to add the Spy Fly to the combat. Now, here's where it gets interesting.

Spy Fly says that nothing other than guns can harm the Spy Fly - "Only guns can harm the spy fly. Nothing else counts, not even your level".

So should that be interpreted as "Only guns can be used for this combat. Nothing else counts, not even your level" or something else? If it is not that, then how do you "allocate" certain items to fight certain monsters? The original munchkin rules say that "If other monsters (a Wandering Monster or a Mate) join the fight, then you must defeat their combined levels". Since the levels are combined and they are fought as a single unit, then I would expect any restrictions to apply to all.