It works with shield block. Which is basically the entire point of its design (offense for defense)
You'll also have some serious wrath starvation issues. That will force you to run a cindercoat and RoRG giving up the damage boost from F+R. Piro is pretty much mandatory. The only shield that you could possibly consider besides Piro is Final Witness, but you will struggle to keep wrath up against lower numbers of targets and against tougher enemies where you need to keep bashing as much as possible.
Blood Brother provides a 30% damage reduction when you block as well as providing more block chance and giving a damage boost when you block too, making it significantly better than coven's
Theoretically the two would stack for even more DR, whether it's additive or multiplicative would mean a lot. Lose all the damage though. Might not result in total wrath starvation, but that's dependent on giving up more damage for RCR in a couple slots.
Might be worth considering in an attempt at Roland's Support though.