Fascinating... This isn't just arcane failure. The ambient energy here is violently skewed by rusted iron and ancient blood.
Decades ago, the legendary hero Tristan sacrificed himself right here to save the swordsman Manji from the Balrog.

Tristan's shattered sword acted as an iron ward, suppressing the beast's dark aura for years. But the Balrog's lingering malice has taken on a life of its own... an entity the fairies here call Caligo.

The local Echopus have absorbed Tristan's rusted fragments. They are bloated on Caligo's malice.
We need some breathing room so we can continue our research.

Can you defeat 50 Echopuss to clear out some of the harmful magic in the air?
They may very well return, but the time in-between then and now should be enough.

Accept: Excellent. The pursuit of knowledge requires rigorous hands-on fieldwork!

Decline: A pity. Discovery normally waits for no one, but please return when you are ready.

Aha! You've done it!
Yes, my instruments confirm it. The magical density is dropping rapidly.

Tristan's physical ward is gone, but by purging the corrupted monsters from the area you have preserved his memory and given us room to breathe.
However, my friend, we have only cured a symptom.

This living malice, Caligo, has taken root far deeper. The true nightmare lies at the absolute core of the World Tree.

You've done a great job today, but I'm sure the natives are in need of a strong pair of hands!