High Summoner Galatea:
I have several ideas for potential opponents for you.
First of all, you should try Summoner Almors. His has been sick lately and is recovering on Talking Island.
You should try Summoner Basillia. I have heard that she is busy researching a new form of Summoning magic nearby a farm on the southern shores of Gludio.
Summoner Carmoniell of the Elves has been in seclusion in a cottage in southern Dion. I've heard he has had some trouble lately.
Summoner Celestiel usually resides in the Ivory Tower, but has returned to the Elven Woods on urgent business from the homeland.
The Dark Elves Summoner Brynthea and Summoner Belthus are proper opponents for you, but they are hard to find, as they are not likely to stay in one place. Last I heard, Brynthea was somewhere in the northeastern parts of Giran, and Belthus was somewhere in the Cruma marshlands...
These Summoners are all proud and haughty people, and may scoff at a challenge from an apprentice Summoner like yourself, but they will likely accept the challenge, even if it is merely to display their supremacy. Return