Activate it first
Right-click the Omen in the inventory so it is active before entering dangerous content.
Character progression mechanic

If your experience bar is at 46%, one death leaves it at 36%. If it is at 6%, the loss stops at 0% and cannot lower your character level.
Death loss calculator
This death removes 10% of the experience required for the current level.
| Content | Experience lost |
|---|---|
| Campaign act area | None |
| Area accessed through a Map Device | 10% of the current level |
| Map Device area with active Amelioration | 2.5% of the current level |
| Pinnacle area where XP is disabled | None |
Right-click the Omen in the inventory so it is active before entering dangerous content.
The Omen does not prevent death. It prevents 75% of the experience loss that would have occurred.
Only one Omen can trigger from combat in an instance. Another combat Omen triggering first can leave Amelioration unavailable for that instance.