Here's me soloing the 45 minute Baron run in Stratholme as a SL/SL warlock with voidwalker.

No consumables were needed during this run, including holy water. However, I did pick up a few waters during the Slaughter Square event, just in case.

Key points:

For the Baroness, went petless (with demonic sacrifice) to avoid any mind control issues.

For the skeleton zerg after Ramstein, used the VW shield and a quick summon, then cast as many seeds as you can. If you can't get them all down, pop another shield or use the holy water you picked up before.

For the baron, had the void tank the whole fight, keeping him up with health funnel. When you get the change, put up siphon and immolate (but not corruption, because you'll be using a lot of seeds). The moment he starts summoning adds, get a seed on him.

This is my first movie, so forgive my crappy editing skills :P.