From Chaos to Catastrophe with The Witches of Karres
If he'd known he was getting stuck with a trio of psi-welding super-beings, even straight-laced do-gooder Captain Pausert might have thought twice about rescuing his two young "witch" charges from slavery on a dark planet. But what's done is done - and with galactic peace once again threatened in the mysterious and pirate-ridden Chaladoor region, only a dangerous mission backward in time can save the present and maybe - get stalwart-but-obtuse Pausert to see one of these young "witches" as more than just a friend.
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Phantoms of Space Opera
The torpedo exploded into a vortex of amber incandescence, far enough away to be harmless, although close enough to set the Venture's radiation detectors squawking.
"Nasty stuff," said the Leewit. "The lead ship is coming into range, Captain." As she said that, the mysterious ship fired two more space-torpedoes.
"Let them have it," said Pausert. "They asked for it. We'll run, if need be, after that."
The Leewit blasted the torpedoes, then launched a volley of purple ova gun fire across space. She did not miss, but for the effect that she had on the attacking ship, she might as well have.
"Give them some more," said Pausert tersely.
It was almost as if the nova bolts were just going through the ship. Pausert checked his instruments. there was something wrong here. the visual and radiation detectors were giving readings - but the mass-detector wasn't. the attacking ships could be seen... but they were as insubstantial as snow-flakes, mass-wise.
"It's Chaladoor Phantoms, Captain," quavered Vezzarn's voice over the intercom.
"What are they?" asked Pausert
"Legends of the spaceways, Captain. You can't escape them, and you can't kill them, either. You can drive a ship right through them, and it has no effect. but they sure can kill you."
"Huh! Those torpedoes sure got hit," said the Leewit. "Anyway, how did any legend start if no one gets away?"
"Well, we're going to get away

I had to dig around a bit in my memory to have everyone and everything making sense - start the series at the beginning, or you'll be adrift in space! (