Oath of Vengeance Prey Guide (2006)

It's the third time you're visiting your ancestors' holy grounds. Go forth. After a short walk, you'll see the familiar fireplace (#403) with Enisi sitting near it. He'll send you to the cave, as you're now mature enough to finalize your training.

Use the stone door (#404) and follow the only available path. Take the artifact (#405) that will permanently increase your health. Enisi will call you, saying that this realm has been attacked by the aliens.

Head back to the fireplace. You'll end up near Enisi(#406) who's defending against Centurion's attacks. He'll disappear, leaving you face to face with the monster.

Kill the beast (#407) and prepare to exchange fire with some more enemies. They'll be coming in several waves. Eliminate them all. When you see the blue portal nearby (#408), cross it. No point casting any more ammo on defending this world. It's already lost.