Monsters:

Dreadwalker.

174.

The dreadwalker is a creature that was created on earth when a scientist discovered an unusual microscopic organism. Through years of its activity, it began to grow to a complex lifeform.

When it grew to full size, it was kept hostile.
The lab was then abandoned, with the people forgetting the creature was ever there.

A phenomena creature known as 174 unleashed the creature.

174 is a phenomenon known as “aprositos.” which is greek for unreachable. It has been around since the first human civilizations. the only way to know its in your presence is seeing a dim irregular shadow, with a dim set of two white eyes.
It cannot be reached, as it is technically an illusion. No matter how far you walk up to it, you will never actually be near it.