Who should I change to take this into brutal?

After complaining last week on Reddit that Hydra is pissing me off, I knew I hit mercy on Void and I found my first Void Leggo, Marichka, and I swear I was not expecting such a performance. I 6starred her and put a very mediocre set on her but oh my days she improved my team so much, I managed to deal 13.4mil last week on Hard and today after a single fight on Auto, I've dealt 26.5. Now, because I'm greedy, I would like to start thinking about going up to Brutal in a while, who do you think I should change in my current team in order to take this higher up, or can I even do Brutal at the moment?