I find it rather unlikely that the Grand Exchange is the result of a Zarosian ritual. The flourishing of trade in the Zarosian Empire was specifically attributed (in the Mahjarrat Memories books) to the standardization of language (infernal) throughout the Empire and its conquered territories.
If a ritual was indeed created for this purpose during the time of the Empire, it would be incredibly odd for Otto either not have been mentioned or to have not been implemented prior to the Empire's collapse.
I suppose it could be a situation like the Salve (use of a modified Zarosian ritual to accomplish the goals of another god/civilization, but, given that the area wasn't resettled until some point in the 4th age and didn't gain economic prominence until the rediscovery of runes in the 5th, I also find that somewhat unlikely but possible given the apparent habitation of Varrock by Zarosians until at least the point that it was still called Avarocka.
05-Sep-2017 10:29:02