In Diablo 4 Season 9, players are introduced to a new gameplay loop centered around spellcraft and jewel crafting. If you're aiming to strengthen your build and boost your seasonal progression, Horadric Strongrooms and Escalating Nightmares are the main activities to focus on. These systems bring consistent sources of seasonal rewards, including Herodric Spells, Arcana, Catalysts, Infusions, and Jewels,  while also increasing the challenge and loot quality.

This guide walks through what Horadric Strongrooms are, how to access them, how to efficiently farm Arcana and Jewels, and how Escalating Nightmares play into the equation.

Diablo 4 Season 9 Horadric Strongrooms Farming Guide

Horadric Strongrooms are a new feature introduced in Season 9 and are now a permanent part of the game. You can find them inside any Nightmare Dungeon, including those within Escalating Nightmares. When entering a room marked by a Horadric Strongroom pillar, interacting with it summons waves of enemies. After defeating them, a portal appears, taking you to a deeper chamber with more combat and decision-making.

In this second room, after defeating more enemies, you’ll be presented with a choice of pillars. Each pillar offers a benefit or challenge, such as increased monster density or bonus attunement gains. Choosing the right ones can greatly impact your efficiency.

Once your selections are made, you enter the final chamber where you have 100 seconds to gather as much Herodric Attunement as possible by defeating enemies. Special interactions like attunement pillars and shrines of sacrifice allow you to spawn more enemies or elites for better results.

Filling the attunement bar or running out of time triggers a boss fight. Defeating the boss grants loot and a chest that contains your main seasonal rewards, catalysts, infusions, Arcana, and Jewel recipes.

1. Farming Arcana, Catalysts, and Infusions

The chest at the end of a Strongroom is the primary source for catalysts, infusions, and Arcana. While Arcana initially had a low drop rate, this has since been patched and improved. Still, Arcana doesn’t drop in abundance, so maximizing your attunement bar is key to increasing your odds.

Catalysts and infusions tend to drop naturally, particularly after completing steps in the seasonal questline. If you're missing these components, continue the questline and then complete another Strongroom to trigger the drop.

One important tip: higher-tier Arcana (rare or legendary) won’t drop until you interact with the Horadric Focus in Serar and claim the two reputation upgrades that allow rarer Arcana to appear. Without these, your drops will be limited to lower-tier Arcana, which can significantly slow your progress.

2. Horadric Jewels and Recipes

Horadric Jewels are crafted using recipes that drop from Strongrooms, but only on Torment One difficulty or higher. These recipes are treated as unique items and once acquired, allow you to craft specific jewels at the crafting station.

While one jewel recipe is guaranteed through the reputation track (Spark of Creation), the rest are random drops from the end chest of Strongrooms. Maxing out your attunement bar improves your chances, and multiple recipes can drop from a single chest.

Crafting these jewels requires seasonal currency and gem fragments. The currency is used both for upgrading spells and crafting jewels, and it comes from Strongrooms, Escalating Nightmares, and especially the Asteroth boss. For gem fragments, look for the “Horadric Gem Reserve” affix on Nightmare Sigils, it spawns chests with gem fragments throughout dungeons.

3. Escalating Nightmares

Escalating Nightmares are another new addition introduced in Season 9, and they’re here to stay. They involve running a chain of up to three Nightmare Dungeons back-to-back, with each one increasing in difficulty and gaining new affixes from the previous ones.

Each dungeon in the chain can contain its own Horadric Strongroom, meaning you can do up to three Strongrooms in a single escalation. This makes Escalating Nightmares one of the most efficient ways to farm seasonal content.

After completing the third dungeon, players on Torment One or higher can challenge Asteroth, a multi-phase boss who offers a generous loot drop, including a large amount of seasonal currency.

4. Asteroth Boss Fight Tips

The Asteroth fight has a few mechanics to keep in mind:

• He starts mounted on a large beast. Once dismounted, the beast teleports to the center and begins healing.

• As the beast heals, a damaging liquid circle spreads across the arena.

• If it reaches full health, the beast revives and rejoins the fight.

• You can either let the beast live and focus on Asteroth, or kill it repeatedly to avoid the room-filling danger zone.

Regardless of your choice, once Asteroth is defeated, the fight ends and you receive your rewards, including a large pile of Herodric currency and gear drops.

5. Farming Tips and Sigils

To maximize your farming efficiency:

• Use Nightmare Sigils or the new Escalating Nightmare Sigils.

• Look for modifiers like:

• Horadric Room: guarantees a Strongroom spawn.

• Forgotten Wisdom: enemies drop XP bundles.

• Horadric Gem Reserve: spawns gem fragment chests.

• Herodric Material Reserves: more crafting materials in Diablo 4 Season 9.

• Equipment Delve: increases equipment quality.

Escalating Nightmare Sigils can drop from Strongroom chests, especially when your attunement bar is full. You can also use the party finder to multiply your efficiency, one sigil per player allows four full dungeon chains with just one sigil each.