Bloods are a joke to get, any 85 can kill the Destroyers in 10 seconds.
A full trash run to kill all Destroyers (around 8 of them, not sure) takes 5 mins, including the time to walk in, walk out, reset.
1 Run (5 mins) x4 (Instance per hour) = 20 Minutes of work for ~2.24 Blood of the Mountain (4x8 Destroyers, each 7% droprate)
Just park an unused 85 alt near the instance.
I know my calculations aren't exact but it still gives an accurate number.