To unlock Helltide players must first reach Nightmare Difficulty. This can be done once the player reaches level 50 and completes the Capstone Dungeon on Veteran Difficulty.
A Helltide is a region-wide event in Diablo 4 that becomes available starting in World Tier 3 difficulty. Helltides feature empowered servants of Lilith with increased difficulty and loot. Helltides can occur in any of the five regions of Sanctuary. Monsters in a Helltide drop a currency called Cinders, which can be spent to open Helltide Chests within the event zone. Dying will result in losing a large portion of your Cinders.
Helltide events begin every 2 hours and 15 minutes. Each Helltide event lasts one hour. See the Diablo 4 Helltides timer for the next Helltide start time.