An archmage in Zigur

[frobnoid]

An archmage who gives up all his/her spells before hitting the wilderness will find Zigur to be visible (no mana bar).
Zigur's shops are closed, it's inhabitants are (apparently) in hiding.

Only Myssil is there, and is hostile.

It's unclear if this is intentional (level 30 boss available right away, what a challenge!), or how this changes the Grand Corruptor quest later on... or if its a bug which confers absolutely no advantage at all.

[Tasidar]

Not even the very wise can see all ends...

[Nussbaum]

or how this changes the Grand Corruptor quest later on...

Killing Myssil before Fall of Zigur quest makes you unable to complete Fall of Zigur and thus unable to get the Corruption/Hexes tree. You will go to Zigur with the Grand Corruptor, but just stand there, no Myssil appearing.