By looks alone, I can base the monster off the story of the "African Bowana Spider." So maybe the monster can enter and control corpses? Or some unfortunate travelers and knights that are caught or killed by a matured version of the monster would be used to house its eggs, and act as something to control by the offspring as they grow? Like a parasitic creature or something.
I like the idea of it taking control of corpses. I can't remember what they were called in Dark Souls, but NecroSpiders or Grave Robber Spiders would fit as a moniker. Perhaps a name like Corpse Burrower or even Puppet Spider
@OtomostheCrazy was more thinking that the monster feeds of the human body until at one point it is able to grow inside. When the monster has enough strength it will take control over its brain and kill anyone it sees as food. After that The human will start to mutate getting those enormous claws and will start to slowly die. And the worst of all of this is that the human is conscious and can still feel everything.