The Fiend's Cauldron is a system that lets the player choose the difficulty of a stage by offering a certain amount of Hearts. It appears at the start of every stage in Kid Icarus: Uprising. The higher the intensity, the more monsters there are and the harder the stage is to clear. However, the higher intensity the player sets it to, the better chance the player has of getting more hearts and better weapons. The lowest intensity on the Fiend's Cauldron is 0.0 and the highest is 9.0. 2.0. is the standard difficulty and does not cost any hearts. Lowering or increasing the difficulty requires the player to spend more hearts. Retreating will make the player lose those hearts.
- 0.0- Effortless
- 1.0- Easy
- 2.0- Standard
- 3.0- Tougher
- 4.0- Challenging
- 5.0- Heatin' Up
- 6.0- Extra Spicy
- 7.0- Infernal
- 8.0- White Hot
- 9.0- Nothing Harder!
Dropping hearts into this pot raises the Intensity, making enemies stronger but also causing valuable weapons and items to appear. If you fail the level, you'll lose hearts, though you can choose to continue at a lower Intensity.
- In Chapter 19, the player can bet more hearts than any other chapter, going as high as 20,000 or more hearts (for 9.0).
- Before moving out, the player can tap on the Fiend's Caulron to give it a nudge, though it does't affect anything in the game.
- As the player raises the intensity, the mood on the Fiend's Cauldron changes.
- When the player dies and the Fiend's Cauldron spills heats, the player can see where the hearts go by pressing down on the control pad. The amount of hearts overall that the player lost will be seen, even if it is a lot.
- The difficulty selection from Super Smash Bros. for Wii U / Nintendo 3DS is based on the Fiend's Cauldron, with a balance replacing the cauldron and coins instead of Hearts.