Updated with lower cost all around to make it more usable.
The idea was for a card with a reusable death effect skill that was reasonably difficult to use but could be powerful given how strongly Death can utilize death effects.
Obviously the first draft was pretty bad. So now here it is with one | two less summoning cost and one less ability cost.
As far as letting it extend to all "dead" creatures, that has too much gray space for my liking. If there's an official list with an actual term for it, then sure I'd do that, but I don't like to use a term that isn't really official. Especially in card ideas.