Euclidean distance outside a Polygon (ArcMap)

I got some university coursework to analyse the best potential areas for a residential development project and I'm currently doing multi-criteria evaluation. One of the shapefiles in the dataset given is high voltage power lines, I created a buffer around them of 200m (a recommended safe distance) and want to do a Euclidean Distance around that buffer closer being better because of cheaper land value.

Is there a way I can do Euclidean Distance going away from that buffer and not within it?

Should I standardise it, change it into points delete points within buffer then change it back? Seems a bit complex. Please say there's an easier way.

Please forgive me if this is simple my degree isn't GIS!