I have no clue why, but it worked better for me when I had Queen P tanking dragon, and khan above that. Seems what all the others are doing. If your entire team is surviving (minus main) then this doesn't matter. (blood/lance could go on the bottom row to kill the AoE guy, if people are dying)
You could try adamanti or lance instead of blood. They did fairly similar damage for me (adam does damage throughout, but isn't as good when it's down to just the dragon), and I guess it depends on stars and saints. Good luck.

