The easy stopgap would be to add feathers to training tower rewards. Badges are dumb.
I had 50 stamina earlier and instead of doing anything real with it I took my modern Arena team to Lunatic 9-5 and 9-2 just to see how it would stack up.
Yeahhh. I've got 20 orbs, but I don't really see the point. Plus, it takes forever to level characters, and if there's a level disparity, it's a nightmare. You pretty much have to stick to units that are basically the same level, or else they can't kill enemies or they don't earn XP from kills at all.
I haven't had this experience at all. I've leveled 7 characters to 40. The first few were just part of my standard team, but Catria, Anna, and Hawkeye were late additions, and it didn't take long to get them there. I did Hawkeye today and yesterday using maybe 4 or 5 stamina bars total? And he's kind of a shit hero. I got 5* Anna to 40 in I'm pretty sure just one day; it helps that she's got better stats.
Leveling even a 2* to 15 or so is trivial. You hit the experience cap fighting same-level things, so it's only like 20 kills to get there. After this, 4*s and 5*s are going to be competitive against clerics and things they have color advantage over even when underleveled, and they'll get substantial experience for killing something 3+ levels above them. So you take them in with an escort that covers their weakness, a healer, and probably a dancer, and you get them 2 or 3 of the 4 or 5 kills on maps that are 3-5 levels above them. They stay pretty safe, especially because the AI will tend to go for your healer even if it could kill the thing you're training. Up to level 37ish I'm only needing at most 4 kills to level up. After that I hunt for favorable colors on the top floor.
I wouldn't spend on this banner unless you are a fan of those games.
I wouldnt spend on the next datamine banner either.
I just hope the choose your hero banner is worth it.
Yes, in retrospect I think the way to go was to spend every available orb on only red stones on Legendary Heroes.