Arcana: Utility Modifiers
Arcana provide spell modifiers—Options like Unstoppable, Vulnerable, or Diablo 4 Items Healing, among others. They are unlocked by:

Seasons' Codex Chapters – Daily and weekly objectives.

Helltide Encounters – Chests at event completion.

World Events & Whisper Trees – Whisper rewards often include Arcana.

Nightmare Dungeons – High-challenge zones have rarer Arcana.

Arcana have three rarities—Magic (base), Rare, Legendary—with differing power.

4.4 Horadric Jewels: Passive Gear Enhancements
Horadric Jewels go into socket slots on gear for passive benefits—boosting your Catalysts or class abilities. They’re acquired by:

Nightmare Dungeons – High reward zones.

Seasonal Bosses / Giants – Dropping Jewels at victory.

Codex Milestones – Lone Jewels infused into goals.

Seasonal Events – Challenge rewards, sometimes hidden or rare.

Jewels also tier in rarity: Normal, Rare, Legendary. Some adapt to cheap Diablo IV gold Arcana themes, scaling bonuses based on the number of Arcana equipped for a specific school (Control, Power, Denial, etc.).