Dwarf room is doable. I did it with two gates, just need to keep barriers up and hit Lady as much as possible to get her armor under yours. It does take quite some time, but it is doable. If you can get into final room as long as Dop does not transform into Gate you should not not have too much trouble. The key is to try and kill and mirror queen(s) at the same time so you do not get an endless amount of high level troops. I left the glass golom alone and let that thing get 1000 armor. Also the room you did not mention which has shadow hunter & dragon is tough. I tried to copy the hunter since it would hit for 600+ and that and the dragon would be a good combo, but that first troop just gets too much purple and the mirror queen dies.
The level 500 delve should be difficult and it is, this delve is different because you have to scout ahead and plan based on the 2nd room and there is going to be some randomness, just have to prepare and figure out the best plan of attack based on what you get. FWIW I like Mirror queen/Dop/copycat/Mirror Queen as my team going into the delve.