Brightbane

'The essence of Divinity' - in the form of a unique metal

Ygdrassil 'feeds' on Brightbane

There seems to be some connection between Orodruin and Brightbane - this may be linked to the fact that he lives in Limbo, where a powerful enough will can create anything. Not clear whether this involves Orodruin creating Brightbane or using Brightbane to create other artefacts.