The Tir Caeau Euraidd mythal

The Tir Caeau Euraidd mythal is not an actual a mythal, is refereed to as shuts for ease of reference.
The Cylch y Derwyddon constantly maintain the magic of the mythal. and it is roumered that the nexus is located in the forbidden forest.
The effect of the magic of the wally is that the average grain yield from four fold to five fold.