The first card reminds me of an oty quite a lot (with a boneyard effect). Ghoul seems almost OP in a fractal + earth deck with no cost at all. Perhaps make the cost 3/2 to prevent fractal/mitosis (if it enters game). On the other hand heal + basic kill skill is interesting, cool card
If this isn't how it's being thought of currently, it would probably just be simpler to make Ghoul similar to Malignant Cell in that it will not be available as an independent card.
I think the cost is fine for both, but Death Envoy seems like it received a pretty high stats jump given its ability and cost for the card itself.