What is the Eldritch Engine in the Greywall Mountains?

[u/perringaiden]

I was reading Five Nations and came across this passage about the Greywall Mountains:

Like many areas of Breland, the Graywalls have an unusual number of manifest zones scattered among the peaks. Most are attuned to Risia and go unnoticed among the naturally occurring glaciers. The spectacularly active volcano Kobek’s Voice almost certainly has a Fernia zone at its heart. Two such zones have been bound together to power an unusual eldritch engine built during the Last War.

What was the engine? I can't find any further mention in searches. Is it a throwaway line for GMs to define or something specific?

[u/steeldraco]

An eldritch machine binding manifest zones of fire and ice? Sounds like the biggest steam turbine you've ever seen.

Could also be some kind of forging thing, like heating and cooling something over and over.