Ruthven is a lot worse to solo now without a pet to let you tank the minions in the fight. It falls into the “Deca wtf” for me same as how Cemetery rework went.
For experiment’s sake I just went in a couple of Manors solo, on no-pet 8/8 tops/pyra sorcerer.
First one I tried the circling the room clearing coffins, but because Ruthven’s bat phase is no longer a fixed time, I couldn’t predict when he would respawn, so I kept missing half or more of his short vulnerability because I was not in a position to attack him (as even a single minion can wreck you). Annoyed/bored with this after 5 or 6 times missing it, I switched to standing outside the room, clearing the one coffin, and going in only when he went vulnerable. Took 20 minutes total and I didn’t count how many rounds.
Second one I did completely by the exiting/entering the room tactic and it took 10 minutes and 15 rounds. Was predictable, and easy, though this same tactic before the rework would take me 4-6 rounds, so a lot slower. Do not like. Though I expect on main+pet I can stay in the room so won’t notice things, it’s harsh on the lower pet players, and why would Deca want to make the dungeon unevenly difficult? I don’t get it.
As to the HP bars you mention @Yasmule I think what’s going on is the bar gets screwed up because Ruthven despawns/respawns, and it resets the calculation each time. The fight has a few phases too, which might mess it up (eg the final phase). So don’t trust that because the bar is fuller, his actualHP has raised, it might be an illusion.