I can see Archive in it. she can rationalize fighting against the Outsiders since they mean death to everything. basically even herself and the Archive entity. Lea and Gruff imho are good candidates also tbh. I mean unless ordered directly to not interfere by the Queens, they are free to act. I mean they could even form a contract to make sure they could get involved.

I have been saying for awhile that the Starborn is more than just a counter to the Outsiders. I mean he is able to generate faith magic through his faith in magic as we have seen w/ his pentagram countering vamps. that could be an extension of his will as well. his use of multiple elemental magics. I mean is there an element he has not yet used? I think wood/ nature maybe. his use of multiple elements in succession is well beyond something a young wizard should be able to use. Lea, " anyone can play w/ an element. few can manipulate opposites w/ such ease." he is versed in mental magic combat as well as necromancy. he has used Hellfire and is currently using Soulfire. he learned how to be a ghost and utilize memories. I mean is there a power he has yet to learn how to use? Starborn, child of the stars, child of the universe. sorry but yeah he is very much an all around terror. is this natural ability as a gifted wizard or is it because he is Starborn.

think Capt Planet except as a wizard.

I see it as he is a member of the Accords, she has a need for Marcone in the future war I am guessing, she needed to show she still was in control and it was a major move by Nemesis and it needed to be countered by throwing the human, mystical, cosmic, monkey wrench..... Harry Dresden into the mix.

Say nemesis needs black magic for some reason, so it potentially becomes vulnerable to that same energy. The whole you can't protect yourself from your own energy thing. Harry using the Blackstaff could turn the power against the bad guys.

^ yup.
this is why I hope he gets some type of epiphany that helps him leave mab and give him some type of resistance to the taint. doing so gives the opportunity to boost and ally, by giving them the Staff. Harry will need support imho.

to me I am not a fan of Simon being Cowl.
for the OP though I did give it a thought and to me here is a good idea, similar to what has been said that he gets room to act.
what if it wasn't just him that left. what if it was a faked mass exodus. what if Simon was body switched by Cowl awhile ways back. what if he was more like kemmler than the other disciples. instead of focusing on one sphere, he was an all around neco like Kemmler. using that position he helped embed Peabody. influencing the Brute Squad. I mean Brute Squad really does say pushing the edge of Laws to me lol. the war was starting and the Black Wizards needed room to prep for it. two fold effect. hurts moral of the Council and giving space to freely act for those that left.

I like this question from the OP. I can see it as going a couple ways. one of course is harry as he becomes like a balance for magic as a Starborn meant to hold back the Outsiders. he will need to be vicious, using black magic so this helps him. (imho I say Harry comes up w/ a way to fight the taint on his own , not needing the Staff. but, I think Harry's Winter link might be a deciding factor possibly.) the other would be either Ramirez or Chandler. Harry will need allies strong enough to fight by his side. giving either would be of a major help. especially since losing the Staff would most likely mean Eb's death imho. don't like LTW would be a good choice. he has major issues and wouldn't fit him imho. although giving it to the Gatekeeper would be sweet. turbo charging a top ally would rock.

to the OP. to me the pentagram to me is more so a symbol of Harry's total belief in magic. he has a true "Faith" in magic. as how he generates his faith magic centered on his amulet. his Mother knew he was to become the "Starborn". she wanted to help him, thus giving him a focus/symbol to help guide him. thus as a side effect he gets a stubborn soul to help give resilience to mind/ soul magics. let him attain soul fire, since he only got a nudge. the rest was on him. so his "Faith" helps him be a strong Starborn maybe?