Have a Horse Friendship Scroll, obtained from the Quest for the Horse Friendship Scroll, and say Horse Friendship Scrolls to Malachai Thanatos, the centaur archer, located in the centaur city.

Gain:

• 9,000 XP per level and, at random either:
• Sinister war blade
• Murder blade
• Centaur Slayer Bow
• Robe of Hell

You can complete this quest at will