[@The Narrator] Thanks for the clarification. I was picturing something more like a Stand, but the way you've just described it makes it seem more like a sentient, ghostly symbiote of sorts that grants its host supernatural powers. 

Can the Memento Mori act independently? Is there like, a range at which they can no longer provide their Revenant with abilities? Does the Momento Mori itself have powers, or is it dependent on its Revenant to fight?