It's nearly impossible to completely abandon 2★ characters, so there's no way you can build a 2★ team then just seemlessly transition to 3★. Between featured event characters and the fact that OBW is borderline mandatory these days, I just don't see playing exclusively 3★ as a possibility. The best advice I can give is to keep everyone (except Bagman, Bullseye, and Yelana) especially 2-4★ characters and level the ones you will use most often, heroes that are tanky and/or have a lot of versatility. This would be heroes lik Thor, Wolverine, C Storm, OBW, Ares, MN Magneto and maybe Modern Hawkeye. The rest are highly situational at best.
I have a level 95 Punisher, but I very rarely use him over something like 85 2★ Thor or even 85 2★ Wolverine. I also have a 90 Hulk that falls into the same category. And my 80 Hood, and 75 IM40, and... you get the idea. They are important to have for featured events for both PvP and the extra required fights in PvE events. If I had to make a 2★ priority chart it would look something like this; OBW > Thor > C. Storm \ MN Magneto > Wolverine > Modern Hawkeye > Ares > anyone else. OBW + Thor is a perfect combo because it covers every color and offers AP Theft x2, a Heal, 2 Decent damage cascade-prone nukes, and a massive AoE nuke. Everthing else becomes situational, but C Storm + MN Magneto is a really solid combo.
EDIT: Also, people are going hard in Starfall. I was playing with 7.5 hours left earlier adn broke 700 just in time to get attacked between ever fight. I shielded at I believe 690 out of frustration and when I last checked was up around 730 in 28th place. I should be a lock for at least 1 Patch cover which is nice, hopefully the Alliance can pull through landing me 2 of them. I was also top 15 in both Normal and Hard for The Simulator nodes but barely in the top 50 for the overall event. Hopefully the required character is something more exciting than my Sentry who only has like 2 covers. Would be nice to see some Dr. Doom or The Hood love.
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