If you make him cheap again and let him kill population, it won't balance him imho. Just add more min-maxing; Mictlan lives with Ermor-style dominions, and still manages to do more or less ok.
Maybe a slight cost reduction, and a Hinnom-style population-eating instead of Reaper effect. (He does not eat people, of course, just causes some deaths now and then). Because thematically, yes, it makes sense.
