GY Law's own leader trigger is based on total combined Character cost on the field, not on DON
I already talked about how good I think these will be in Legacy at length last week, but I just wanted to mention here that between fetchlands, Serum Visions, Sleight of Hand and Gitaxian Probe, Modern also has most of the tools necessary to enable them, so I expect to see a splash there too, though maybe a slightly smaller one
Youll also just get a lot of card advantage this way
I'm going to talk about each card in this category
On the other hand, the city of Naktamun was probably pretty close to resource capacity, even assuming the mummies don't consume any resources, so the living population was close to, if not actually, being maxed out, and HoD would push the resource cap down by a lot