The Hero's Challenge

Overview
Summary Obtained from
 * 1) Enter the Frozen Forest from the Iron Mines of Moladune.
 * 2) Follow Sanyi through the mountains.
 * 3) Defeat Sanyi the Soul Eater.
 * 4) Return to Vanyi for your reward.
 * Vanyi in Droknar's Forge

Requirements
 * Completing a professorial Path quest:
 * The Elementalist's Path
 * The Mesmer's Path
 * The Monk's Path
 * The Necromancer's Path
 * The Ranger's Path
 * The Warrior's Path

Reward
 * 5000 XP
 * 15 Attribute Points

Dialogue
 * "Your aura is radiant. Aided by the spirits of the desert, you can learn any profession, master any skill, but there yet remain untapped reserves of power within you.  Take my advice, go to the Frozen Forest from the Iron Mines of Moladune, and seek out my sister Sanyi.  She will help you unleash this hidden power."

Walkthrough
Sanyi stands in front of the southern entrance to Copperhammer Mines outpost. It is not required to go there from the Iron Mines of Moladune (although probably best), you can also take the walk from Droknar's Forge or Ice Caves of Sorrow.

When approaching Sanyi (you don't have to speak to her, just walking next is enough) she will request you to follow her through the mountains and start walking. From the exit of Copperhammer Mines she will head to the left down into a valley which is swarming with Stone Summit. No worries, they won't attack her, but unfortunately she will stay there until you walk close to her again, which means you will probably need to clear out the whole area of every single dwarf, which requires a quite strong party and careful manoeuvring. You can also rush in and try to escape using a skill like Sprint. You will also encounter some mobs unusual for this area: Two level 22 Mragga Spawns.

Sanyi will finally continue further to the left up into a small valley where she'll wait for you to speak to her again. If you didn't kill all the Stone Summit you may get there without fighting nonetheless by hugging the left wall.

After walking close to her again, Sanyi will start talking once more and finally transform into the demon Mragga (level 28 Necromancer). She will also call three more Mragga Spawns to her aid. But compared to the hordes of Stone Summit on your way here this fight is ridiculously easy. Take her down and return to Vanyi (who will have a perfectly plausible explanation for this) for your reward. Necromancers may want to use the Signet of Capture to get Grenth's Balance from the Mragga.