Deus ex Machina: Guilty or not guilty?

I tread a patch of thin ice here. My world–our own distant past with a twist of magic–has no strict, uniform magical system; at least not one that is known to its people. My characters have no superpowers. Unusual abilities, perhaps, but they don’t rival the forces of nature. The gods keep their noses out of things. They are seen in a few muddled dreams and visions. A reader might see these as figments of the characters’ imagination.

However, I take out one of the bad guys with an amazingly coincidental bolt of lightning.

No one (in the story) can explain it satisfactorily. On one hand, my MCs are accused of calling down the fire from the sky by sorcery (a delightfully vague concept). On the other hand, some people insist that the Good Spirits were ticked off at the deceased. The fact that one of the good guys all but had to be carried away doesn’t bother either side.

This ambiguous event is entirely in the realm of everyday possibility. Stand out in the open when a violent summer storm is approaching and…POW. There is a high probability of lightning striking just ahead of a storm; you don’t have to be in a downpour already. No need for threads of stray magic to act as a lightning rod, either, but they were there.

What none of the surviving characters knew at the time is that the thunderstruck man posessed–and was possessed by–an ancient talisman that contained the demented soul of the sorcerer who created it. What’s more, it held power stolen from many others, and an uncertain number of trapped souls collected over thousands of years.

Perhaps the talisman was close to some kind of “critical mass”. At any rate, it hungered for yet one more soul–that of my main MC. Its owner, who had hoped to use it to increase his own power, was thwarted and angry. The escaped sacrifice was tantalizingly close again. A thunderstorm blew down from the ice-capped Tatras to bedevil the Krakow uplands. Was it a logical consequence, or was it a DEM?