Checkpoint

Let’s pull all these fragments back together and see what we have. Here’s the original snippet:

A soft hissing sound. Behind him, above him. It set his teeth on edge.

He turned round, looked up – and nearly bit his tongue off.

Because the crack in the sky was back.

It was bigger. Much bigger. It covered a whole quadrant of the sky now. It was shaped like a great black V: a sharp-edged shadow where the night’s darkness looked even darker, somehow. Thicker. And all the way through it, he couldn’t see a single star.

The stars had disappeared.

Lucky wanted to say something, to warn his mother or cry out, but he couldn’t. His mouth had gone dry. His throat constricted. Looking at the thickening shadow, he couldn’t even breathe...

Phoenix

Here are the examples we've been building:

A deep rumble. Below the ship. It rattled his bones.

Biff looked out the window - and nearly choked.

Because a great, crackling void was opening on the surface of the planet below.

It was expanding. Rapidly. Soon there was little left of the colony as the buildings were swallowed. An enormous red fissure, like jaws slowly opening: a fiery rift that looked hotter than a sun. Angrier. And all along its length, the surface of the planet was sucked into the abyss.

Nothing escaped.

Biff wanted to alert the crew, to blast the engines and get away as fast as they could, but he was frozen. His limbs were suddenly so heavy. His head spun. Looking at the destruction below, he wasn’t even sure if his heart was beating...

Something was beeping. The gravity probe. She smacked it without thinking.

Then she saw the monitor—and her heart stopped.

The black hole was alive.

This monster was already the size of a solar system. The mass of four million suns compressed into a black sphere that broke the local universe. And now it was unravelling. Like an octopus unfurling its tentacles. A dozen black tendrils emerged and probed the inner rim of the galaxy.

It was looking for something.

Vijay wasn’t one to panic, but this had her frozen. Her jaw hung open. Her mind was blank. Seeing a million suns vanish before her eyes, she was seized by the thought that if she moved, then this thing would see her, and would reach out for her...

A low mechanical vibration. From behind her. It made her gills quiver.

Jola twisted, just in time to see—and swam for her life.

The human’s box was glowing, pouring light from every corner.

It erupted in an enormous detonation. Exploding into a blazing ball of force and metal: in the blink of an eye it grew so large it consumed the ocean shelf the box was sitting on. And it only got larger, consuming everything close and pushing the rest away at an impossible speed.

It was death.

Jola was in so much pain she almost wished it had consumed her too. Her skin felt burnt. Her bones felt broken. Thinking, even briefly, about all the life that had just been ended by the blast, made Jola feel like her heart would break, too.

And below is your version, joined together. You'll need to delete the line breaks to create a continuous paragraph.

Is there anything you want to edit? This is your last chance to make improvements before we conclude the lesson!

Make sure you:

Create suspense—let the tension rise as you first introduce the threat.
Reveal the threat and show the reader the immense scale of the threat.
Drive home the danger by describing your character's response.

Delete excess paragraph breaks and polish your scene.

Science fantasy worldbuilding in Phoenix 7: Cosmic threats