As a PSA for new players, some water nations would give their gods left nut for a beachhead, as some Water nations capacity to fight outside the ocean is terrible.
So if you see a coastline of independants near a sea with a Water nations, take It.
Note: Yis is the one Water nation where this doesnt apply, their sacred knights are stronger outside water.
My own made up C'tan, depicted by the far more talented than me Rollee.
The idea was a C'tan who is enormously pissed because he preferred being a sun eating space cloud, and is gonna take it out on everyone, trying to sate it's endless hunger the only way it knew how. By feasting on the heat of anything around it.
This tends to freeze things over.
Because it was causing terrible PR with the Necrontyr, the Deceiver, Nigtbringer and Void Dragon tag teamed his ass, ate a good chunk of it, and gave what's left to the owner of the last world he tried to freeze over.
Nowadays he isn't technically a C'tan shard, but is still far too weak from getting mostly eaten, and as such it is transcendant shard level.
They don't let it out much, for obvious reasons, but it's prison can't wholly contain it and thus the world is trapped into, once a desert worked, became a frozen planet during the great sleep, for the shock of the planets Overlord.