H. P.'s Book

H. P.'s Book is an War Mode item used to summon the Cthulhu Mythos. There is a 0.1% chance whenever you go from the Underworld to the Overworld of the Overworld to the Underworld to appear in your inventory, and if you have no space when a space appears it will come into your inventory. When used it gives you the choice: "Vultis scire hoc facere voluisti?". If you click no it goes back into your inventory and nothing happens. If you click yes the Cthulhu Mythos starts.

Trivia
H. P. Lovecraft wrote a book called the "Call of Cthulhu" and other short stories.

Disclaimer
I will not add Cthulhu/a Final Boss/a new mode because if I do everyone will be mad.