Mark of the Spellblaze
The Mark of the Spellblaze is a zone that can be found randomly inside the Charred Scar (an area just west of Dreadfell). It appears as a red magic circle and is easily identifiable.
The zone has a number of enemies, including cultists, blood mages, carrion worms, Gwelgoroths and the occasional lesser or greater Faeros in the early sections, with corruptors joining the list further in.
The terrain is mostly rocky with magma on the deeper floors with burnt trees breaking LOS. The terrain effects in the area include Spellblaze Scars (bonus to spell crit. chance and extra fire and blight damage).
The boss of the zone is the Grand Corruptor, a tough spell caster with support from surrounding enemies. If you yourself are a spell caster with enough spells (10 talents with "Is spell=true" in their description), around halfway through the fight he will make you an offer. He will ask you to attack the Ziguranth base of Zigur, claiming he has been massing forces for an attack for some time now. If you agree he will teleport you into Zigur, where you will have to kill the inhabitants, including their leader, a powerful boss. Completing this quest will unlock the Corruptor class for character creation in future games. The quest will also reward the locked Hexes tree, and will unlock it for the Reaver class, since they start with the locked tree.