o-ring should be sideboard. use that space to put another b-throne vamp. and maybe consider lingering souls

splash red instead to get stromkirk noble? make it 4 cavern of souls and splash red to make it vampire tribal. He's the only solid one-drop vampire.

i think you should replace he supreme verdicts with bloodthrone vampires. gets rid of blue, sticks with vampire motif, and gives you a sac outlet to trigger blood artist whenever you want