Well I don't know if this has been posted before or not, but just incase nobody posted this yet i'll post it :-)
If you're having problems in Black Morass (heroic or normal) there's an easy way to get some more time to ress people and drink.
The bosses at the portals, where the rift lords also spawn have a range limit where you can fight them in. If you make them running out of the range limit, they will simply evade which gives you the time to ress people, and restore mana / health / rebuff. For example: when the boss spawns, aggro him and just run to the portal where Medivh is all. Boss will evade, and reset after like 30 seconds. Waiting for someone to get in his aggro range.
I don't know if this is working for rift lords, but it does work for the bosses atleast.
Actually i think this does work for the normal rift lords too, but i won't confirm it until i'm sure of it :-)
But heyatleast you can do Black Morass in parts now, instead of everything in 1 rush
Again, sorry if this has been posted before, just foudn it out yesterday..