The Core is the main reactor of Warthael, which is located under Zahk. It was created by Izarik Val, mother of Irilath Val, High Priestess and Member of the High Council of Wisdom, in the Year 56, 1Æ. It was build to be the central source of power for the laboratories and factories in Warthael.
The Core is basically a gigantic steam generator, which provides the steam for the rest of the city. It's permanently being fillled with Water, which is generated by infusing the Alladrim'estral with blue mana, which is done with golems managed by Danarian. It's heated by a gigantic oven around the Core, which is fueled by coal from big coal desosits which sorround Warthael.