In a party have the Drk communicate with the Healer. As ironic as this may sound the Drk is healer reliant in certain situations. Telling the WHM not to Holy like a loser when Bloodprice is up might also help. Since enemies will be stunned(and build resistance) and starve the Drk of MP. Usually if a Drk and a Healer are on the same page battles run much more smoothly.