The Grey
The parallel reality. At first glance, there's nothing. The house you were next to is there, but the doors are broken and no windows. There's dust and sand everywhere, if you're unlucky you can see some fossilised bones. It's silent, no birds, no animals, hardly even any wind. What was bright is here almost devoid of any colour. Everything screams that this is a plane abandoned or destroyed by something. And you can't shake the feeling of being watched, there is no rest here. Only a prolonged sense of dread.
People who’ve spent a lot of time here feels restless even outside of the Grey, they get paranoid and swear that they see something in their periphery. And here’s the thing: they don’t seem to be completely wrong. The Grey is inhabited, but no-one who have truly seen it has lived to describe it fully.
How to enter/exit
Most common are spells like blink or plane shift (had this been D&D) but also fixed tears of the fabric and specific buildings that exists in both worlds. The safest of these are blink, it guarantees you a way home.
One of the fixed entires are the Wyrmwitch's Cabin in the Wyrmwing Woods, it is not considered a safe point on entry. It's rumoured that there is one somewhere in the Red Forest and another one all the way in Fallow.