The Entity

The Entity is… well, something. A whisper, a shiver, a trick of the mind that always seems to be standing just behind you when you turn around. Those that are aware if it don't know whether it’s a god, a demon, a sentient magical disease, or simply a cosmic prank being played at everyone’s expense. Whatever it is, people unfortunate enough to tangle with planar keys—or, at least, the materials needed to craft them (Psioclasite, Concentrated Elemental Essenses and Infernal Metals)—tend to end up in its rolodex.
  If the planes exist in a finely woven tapestry, The Entity is the loose thread that makes the whole thing unravel when you tug on it. Naturally, some people insist on tugging.

What's known?

It Leaves a Mark.

Those who’ve fiddled with planar keys, like Dimsum Gyoza, have been nudged by it. Subtle suggestions, intrusive visions, the occasional poem written in terrible meter—it never speaks directly, but it gets its grubby little claws into people all the same. Others that have met a grim fate due to its influence are Godfrey Cantrell and Baldur Forgebrair.

It Wants Something.

Wherever that is... Trouble is, it looks suspiciously like tearing holes in reality.

It Doesn’t Do Manners.

Don’t expect straight answers and friendly conversations. It won't give you a polite knock on the mental door. The Entity communicates through visions and imagery.

Known Encounters

The Bad Poem Book.

The Entity seemed to take a personal interest in writing little riddles and verses in it. They were terrible poems, yes, but terrifying all the same.

Planar Key Users.

Anyone using one of these too much tends to hear a whisper, see a shadow, or feel like their choices are being guided by a hand that isn’t there. Convenient, sometimes. Disturbing, always.

How to Stay Safe (Allegedly)

  Don’t Use Planar Keys. Obvious, but ignored constantly.
  Don’t Read Strange Books That Write Back. Again, obvious. Again, ignored.
  Don’t Be Interesting. The Entity seems to have a taste for people who meddle with planes and generally act like nosey little gnomes. If you’re boring enough, it might just leave you alone.
 

Final Notes

  Is it a god, a monster, or just the universe’s biggest “do not press this button” warning? No one knows.
  It lingers in the corners of planar research, waiting.