Defeat Vorath and the next difficulty opens. Pick it at the waypoint when you choose a destination. Each tier is its own dungeon (the same zone on another tier is another dungeon). The next tier opens when you defeat Vorath, or a guardian deeper than him, on your highest unlocked tier.
| Tier | Monster level | Life | Damage | XP | Loot | Magic packs |
|---|---|---|---|---|---|---|
| Normal | – | ×1 | ×1 | ×1 | ×1 | – |
| Ashen | +5 | ×1.25 | ×1.1 | ×1.6 | ×1.3 and better rarity | +8% |
| Scorched | +11 | ×1.6 | ×1.25 | ×2.4 | ×1.7 and better rarity | +16% |
| Infernal | +18 | ×2.2 | ×1.5 | ×3.6 | ×2.3 and better rarity | +24% |
Higher monster levels also mean a higher item level on drops, so better mod tiers. The ladder has a board for each tier.