There are only four stages (regions) of the underworld, which mean that it takes approximately between 30 to 60 minutes for you to complete. They are Tartarus, Asphodel, Elysium, and the Temple of Styx. The enemies will get stronger the higher regions, so you must get used to them and remember all skills and learn how to dodge their attacks.

Whenever you defeat a boss, you'll get a "first time" reward which will be the following:

1. Tartarus: 1 Diamond
2. Asphodel: 1 Titan Blood
3. Elysium: 1 Ambrosia
4. The Temple of Styx: 1 Titan Blood

Second time you defeat the bosses, the rewards will all be Darkness. So what is count as "first time" rewards? In the game, there are 6 weapons, each time you use a different weapon, it will count as "first time" which allow you to get these rare rewards again. You can also obtain "first time" rewards by increasing "Heat" from the "Pact of Punishment" which you can unlock by completed the game once.

You may also find chests randomly while fighting your way out of the underworld. These Inferno Troves contain one of the items: Gold, Darkness, Health, or Gemstone. Upon opening them, enemies will start spawning and you'll have to kill them as soon as possible because the value of the item in the chest decreasing at the same time.

Chaos Gate is a gate that can teleport you to the realm of Chaos. Upon entering the gate, you'll have to sacrifice a portion of your health. The Chaos Gate will randomly appear through out the regions. There, you'll find Chao who will aid you with his boons. However, the boons provided by Chaos have a certain condition to fulfill before it's activated. I recommend you should always enter the Chaos Gates whenever possible because you'll have to build a bond with Chao as well as fishing some rare fish that only exist there.

Similar to Chaos Gates, Inferno Gates do not spawn until you completed the game once and purchase work order "Gateways, Erebus" from the House of Contractor. You do not lose health when entering the gates, but they require certain amount of Heat from Pact of Punishment.

1. Tartarus requires 5 Heats
2. Asphodel requires 10 Heats
3. Elysium requires 15 Heats

During your journey to the surface, you may encounter mini-bosses in each region and in the Chamber will always be the boss guarded the regions.

1. Tartarus: Doomstone, Inferno-Bomber, Wretched Sneak.
2. Asphodel: Megagorgon, Skull-Crusher, Spreader.
3. Elysium: Asterius, Soul Catcher.
4. The Temple of Styx: Bother, Gigantic Vermin, Satyr Cultist, Snakestone.