Is this Nikola?

[tedric]

In trunk, I just encountered an invisible monster on Swamp:1 that threw lighting bolts and seemed to blink every other turn, to the point where I couldn't even remotely get a fix on its location (no source of sInv yet, tried ?fog to no avail before ?tele-ing away). Is this Nikola spawned with an unlikely and unfortunate /invis, or something else?

[Azrael]

No, it's most likely a vapour. If it was Nikola, you'd already be dead; Chain Lightning is not the kind of thing you shrug off.
Vapours are annoying, but not really that dangerous. It's permanently confused, so it won't follow you. It'll just kind of throw out lightning bolts in random directions once in a while. If you can get sInv feel free to kill it, but otherwise I wouldn't bother.

[XuaXua]

It was a vapor; I had one today in Swamp. Same thing.

[diviton]

If you came across an invisible monster shooting electricity in the Swamps and you survived to tell the story, then it definitely wasn't Nikola.

Twas a vapor

[tedric]

Huh. I guess I've never encountered a vapor without already having Sinv. Hooray, back to Swamp!

[tedric]

So I return to S:1 and literally bump right into the damned thing again in a relatively tight section. What the heck, I think, and wave my battleaxe around a couple of times.

"You feel a bit more experienced!"

Damn right.