I used to be able to solo it no problem but I haven't been (at all, let alone solo) since the revamp and I'm curious to what's different.
the only difference is that you use double strike on dark father now instead of AI (its now immune to AI).
Whirlwind spawn as it comes. i like 100 resist spells or blood oath from the liches becomes a problem.
Also there new mechanic for the flesh renderer room. when your mortaled (and it turns yellow, so no life from attacking when yellow) use confidence spell, or remove curse apple / pots to heal up. I also leave my mount outside for this one so it doesnt die (i use swampy and your dismounted like the whole fight)
This is for sampire solo.
other bosses are the same or nothing i could find that required change of tactics. some might be immune to AI as well but just use double strike if they are.