Earthblood is an incarnation of raw Earthpower.
One may ingest Earthblood only once, but it grants the imbiber the Power of Command (Kevin's 7th Ward).
The Power of Command allows the user to command the Land to do anything the speaker desires, to the limits of its ability. Even extant Laws can be broken by use of a Command. Theoretically, the Land could be Commanded to sink into the sea, or new mountains created.
The one known use of the Power of Command was by High Lord Elena, which resulted in the breaking of the Law of Death.