“They die when they’re killed, and physical attacks are reasonably effective against them. Now, there are some who cover themselves with a veil of mercury, strong enough to deflect thousands of bullets. There are others who can transfer their consciousness and extend their lives with the aid of insects embedded in their bodies. But... well, the former type has no defense against an anti-tank rifle, while the latter type almost certainly couldn’t survive a precision missile strike.”
They may well have figured that Faldeus was joking. The camouflaged men struggled to suppress their sniggering.
But the moment they heard the next thing Faldeus had to say, they all fell silent.
“There are exceptions, though.... For example, this fellow, who wasn’t even here in the first place.”
“...could I ask you to elaborate on that, Mr. Faldeus?” inquired one of the gunmen, ever-so-formally. Faldeus cackled and tossed a piece of the corpse’s flesh at him.
He caught it staidly. He looked at the piece of meat, likely part of a finger, and gasped with surprise. “...wha?”
Under the illumination of his flashlight, it was clear that white bone protruded from the red sinews of the flesh. But there was something wrong. Something unlike the flesh of a true human. Transparent threads, not entirely unlike fiber optic cables, extended out of the flesh and wormily wiggled about in a most disturbing fashion.
“A cyborg, so to speak? Well, we call it a puppet. Mister Rohngall is a terribly cautious investigator, you see. He’s not so foolish as to come all the way out here with his real body. At the moment, he’s probably situated either in one of the branch chapters of the Association, or in his own atelier. I’ll bet he’s all in a tizzy now!”
“A puppet...? That’s preposterous!”
“It is something of a spectacular technique, but do notice that he wasn’t able to make it seem perfectly human. The form of an old man works well for concealing those imperfections, I suppose. I hear there’s a puppetress whose dolls are utterly indistinguishable from the bodies they’re modeled on... they’d even pass a DNA test.” Faldeus talked and talked, sounding disinterested, as if he were an uninvolved third party.

Fate/Strange Fake, Volume 1, Extra