It’s been roughly 3 weeks since the new server was launched. I am 60% of the way through hell mode in the story with my team of a warrior, priest, and two mages. Keep in mind that I’ve made purchases to speed things along, so don’t be discouraged if you are playing for free. You can and will get there eventually. I know because I played for free on the last server. It just takes longer. That’s all.
I could continue on this path and finish hell mode relatively soon, but I’m going to have a problem. This team isn’t very optimal for the arena. It’s worked great so far, but mostly because I’m temporarily overpowered. Zipping through story mode has given me extra resources to boost my heroes.
I now have two conflicting goals.
- Continue to advance as quickly as possible in the story to finish it off and maximize the ongoing resource generation that the story provides.
- Stop advancing in the arena until I’m sure that I’m not getting in over my head in a more difficult league. The last thing I want to do is advance too fast and lose most battles. I think I can advance just one more league before I really need to slow down. As I look ahead two leagues (League C), the guards are starting to look too dangerous. Maybe.
So, here’s my plan. I continue to use my warrior, priest, and two mages for the story. I will swap out my priest for a weak and expendable 3rd mage (which will someday be made powerful) for the arena
I think I can level my priest without advancing in the arena since my priest will be removed from my arena team, at least in theory. The stronger priest will help me finish the story. I will also continue to make my two strong mages even stronger. They’ll be useful in both the story and arena. I won’t be improving my warrior much, if any. I will be advancing my weak 3rd mage, but not to the point I advance a league in the arena before I’m ready, hopefully.
This could go badly. I’m having to somewhat guess how powerful my arena team can be without advancing. I’ll try to err on the side of caution. If I advance unexpectedly, there will be no way to undo the mistake.
Arena Team: 2 strong mages, 1 weak mage, 1 weak warrior. Weak mage sits behind weak warrior. Weak mage expected to die quickly, but at least draw fire.
Story Team: 2 strong mages, 1 strong priest, 1 weak warrior. Team can definitely finish the story.in hell mode, and when I say weak warrior, I really mean lower level 6-star warrior with last stand skill.
So anyway, that’s my plan. Could be a good plan. Could end up being a cluster@#$&. 
You might be wondering why I’m so focused on 2 strong mages. I consider a mage to be strong if it can kill a monster with 1 normal attack in story mode. There’s a huge difference between almost killing a monster and killing it. I would argue that a mage who can kill with 1 attack is roughly twice as good as a mage who needs 2 attacks, even though the game’s power levels might show that the stronger mage only has a slight advantage.
The same holds in the arena. Almost killing an opponent’s hero might be nearly useless, if the opponent’s hero then attacks one of your heroes and kills it.
Update: Plan tossed. Managed to finish story in hell mode with original team of a warrior, 2 mages, a priest, and 7 good pets. Don’t ask how many times I had to replay 10-10 before a miracle occurred (most fireballs hit/killed two targets and both mages used Arcane Blast optimally together to instantly kill one set of 6 monsters).
Ugly battles, but eventually squeaked through. Here’s the team that did it. 
Hopefully, will move to League D next with this team and not League C. I think that will happen, but who knows?
Hope this helps those still deciding which heroes will get through the story quickly. Do note that my heroes were intentionally not equally leveled. It is vital that the mages kill monsters quickly.