Dripping official website schedule is here.
These wallpapers are based on original artwork by the incredible Tim Brawner, who can be found here.
These lock screen wallpapers are not official and may have mistakes.
Scroll to bottom for instructions for use.
Instructions for use (on iPhone): Download > Save to Files > Open In Downloads > Save Image > Open in Photos > Click icon on lower left of image (the one that looks like an arrow pointing up from within a square) > Use as Wallpaper