Difficulties

It Lurks Below has four difficulty levels: Normal, Nightmare, Hell, Inferno. As with Diablo and other games of the ARPG genre, each subsequent difficulty ramps up the monsters levels and reduces your resistances.

Normal difficulty

• Monster level 1-35

Nightmare difficulty

• Monster level 35-65
• All monsters possess deadly Monster Modifiers
• On Nightmare, players suffer from the Nightmare difficulty debuff:
  
  
  
  -50 to all resists

Hell difficulty

• Monster level 65-90
• All monsters possess deadly Monster Modifiers
• On Hell, players suffer from the Hell difficulty debuff:
  
  
  
  -100 to all resists

Inferno difficulty

• Monster level 90-110
• All monsters possess deadly Monster Modifiers
• On Inferno, players suffer from the Inferno difficulty debuff:
  
  
  
  -150 to all resists

World Books

Sold at  Wizard of Space and Time . They allow you to reset the world below Dirt Layer and Badlands, spawning in new monsters.
- Don't worry about your buildings disappearing, only the areas below Dirt Layer and Badlands get respawned
- The books get re-stocked every in-game day (midnight)
- Be careful when you first enter a higher difficulty, it sure is a step-up

 Normal World Book

• Resets the world on Normal difficulty
• Costs 100 gold

 Nightmare World Book

• Resets the world on Nightmare difficulty
• Available for purchase at level 25
• Costs 1000 gold

 Hell World Book

• Resets the world on Hell difficulty
• Available for purchase at level 55
• Costs 5000 gold

 Inferno World Book

• Resets the world on Inferno difficulty
• Available for purchase at level 80
• Costs 10000 gold