Yes, I completed the whole intermediate challenge with less than fully Ascended level 4s.
here’s the team + battle items I used to finish the final intermediate boss stage
My normal team has Richard, a 5 star blue, in it, so it was lucky I pulled Grimm last week and leveled him up. My normal team also has Tiberius, a 4 star purple with Ramming Pulverizer, and he is with the rest of my 4 Stars - Tier 3 level 60 waiting on materials for his final ascension.
My first try at the boss level, there were so many purple reflect guys, I mistakenly tried to save Tiberius and wasted a lot of resources that way. Your purple guy is going to die. That’s why I picked Cyprian - i got riposte up once or twice and punched back at them before he died.
I was also very careful with my items - I have two healers, so I didn’t take any heal potions. I also saved ALL the arrows and axes (5 each), small anitdotes (10), and 8 of the 10 small mana potions for the final boss wave. Take the small antidote so you have more of them.
On the 2nd to last stage, I made sure most of my guys were charged up before killing the final enemy. At the boss wave, I first shot both an arrow and an axe (the combination of miss chance plus reduced damage when they do hit really helps keep guys alive). FYI, I was also totally unconcerned with time as it was more important to think out the board so I can beat the stage and get the completion ascension material prize. Then I used Boldtusk’s attack buff and started hitting with gems. As soon as the arrow/axe effects ran out, I would redo them, repeating until all 5 of each were gone. For the antidotes, there were two bosses that inflicted status effects - the green one with damage over time (green poison icon) and a purple one that reduces healing. As soon as I was hit with the green effect, I’d use an antidote as that damage will massacre you. For the purple effect, I’d wait to get rid of it until I had a heal from Mel or Boldtusk charged and ready to go, or if while waiting for that, I got hit with the green damage over time.
Then based on the board and how the early game played out, I concentrated my attacks on whichever of the front enemies had more early damage, so I can knock one out sooner. When the final boss was dead, i only had 2 heroes left alive and they were both on their last legs.