Device, method and assembly for wound treatment. Specifically a wound dressing device； an assembly, e.g. a kit-of-parts, including the device as a component； and method of wound dressing and use wherein the device is a key component. The device includes a cavity defined by concave walls surrounded by lips for attachment to skin in fluid tight manner and a closure removably fixed to the lips and sealing the cavity. The assembly also includes, as another component a device for introducing blood into the cavity after it is fixed over a wound to permit the blood to clot over the wound within the cavity. In use, the clotting mold device is fixed on top of a wound, and blood is introduced into the mold space to permit the blood to clot within the mold space to form a blood clot over the wound.
