The Hell biome is a very dangerous biome found at 3400+ ground level distance or 40+ underground level distance. The Zombies are extremely versatile and the Undead Dragon nestles here. In Endurance, it is a good idea to make a strong shelter that is free of Bloodstone for they can spawn inside, on top and around. Furthermore, it is a good idea to own High Tier weapons such as the Laser and Bloodstone weapons along with lots of ammunition to fight your way through until you reach the Heart of the biome. If you dig too far down, you will either hit Bedrock which will slow your progress down in a Firefight and slowly kill you; or mine Bloodstone which later results in falling into a pool of Lava. If the player remains submerged in Lava for more then a second, they will take 2-3 hearts of damage for every second being in it. It's also best to be even more cautious on Endurance mode since you can't save your progress.