Hounds of Tindalos

The Hounds of Tindalos live in the distant past, when life was still single-celled. They have the ability to use the angles of the world as portals, travelling through both time and space. If a person becomes known to a Hound, it will hunt them relentlessly.

In the RPG...

Though not specified in the 7e Malleus Monstrorum, the old edition said that the days taken for a Hound to catch its prey is their distance in years divided by 100 million. So, for example, if someone looked through a magical gem back 3 billion years, it would take a Hound 30 days to find them—or 16 hours to find someone who spied the end of the dinosaurs.

    As mentioned above, they can step through any angle that's less than 120°. And they can twist space around them with various effects. They are also said to have a foul odour that will cause vomiting if failing a CON roll. All of these abilities are shared with the Lords of Tindalos and Tindalosian Hybrids (to varying extents). 

    A Hound can use its tongue to drain an average of 10 POW from a victim, though they are more likely to use their claws. If they do, the attack comes with a disgusting addition—some of the blue ichor that covers the creature gets onto the victim and does an average of 7 damage each round until it is cleaned off. Combined with the claws themselves, and the Hound's damage bonus, this means the first strike has a 78% chance of killing an average person. The Hounds also have 2-point armour, regenerate 4 hit-points per round, and are immune to mundane weapons. In summary, they are very bad news.

In a video game...

The Hounds of Tindalos are fan favourites, so it would be a crime to leave them out of a Mythos game. Due to their extreme difficulty level and weakness only to magic, however, you would have to provide the player with the means to stop it, as standard weaponry would be useless. Or perhaps even just as an Easter Egg, with an NPC boasting about his visions of the past or such, only to be attacked out of nowhere by a Hound of Tindalos, which then disappears after the kill.

In a film...

Seeing a Hound of Tindalos on the big screen would be awesome. With all their abilities, there is so much that could be done with one.