Can I ask: do you like the difficulty of the last stage? If they did bring back CotS, would you like a higher difficulty throughout the game? Is there anything major you'd really want to see changed?
The mode absolutely needs difficulty settings.
While you do get experience for losing, I think it would be frustrating for many players who aren't great at fighting games if you increased the difficulty throughout with no option to put it back down.
The difficulty spike in the last mission isn't fantastic from a design perspective, but I feel it could be mitigated if you were given an opportunity to learn how to approach it. The problem is the tutorial.
When I first played CotS, I had absolutely no idea that you could even change a unit's type, or why I would want to. This system is something that should've been taught to you right from the start, and should have been more consistently necessary throughout the mode. Instead, it wastes this important time with 3 near-identical missions that only cover the very basics.
A good tutorial is the difference between a frustrating challenge and a fun challenge. This mission is entirely different from the rest of the mode, as it requires you to understand the intricacies of the way units fight on the field and use it perfectly as you can't respawn, and the mode never gives you a reason to learn about any of this ahead of time in a safer environment.
Other than that, the general approach to difficulty is pretty good. The optional challenges with the main cast are good fun, I think the difficulty curve is pretty spot on, it just needs difficulty settings to just translate that curve higher or lower.
Changes? Other than what I just went through:
- Making the AI more active, more often, just so you might have to adjust your strategy a little. I don't feel CotS was ever meant to be an incredibly complex strategy game, but it should at least require some thought. There are several maps that you just walk through completely unopposed.
- The system that allows you to place units at the start of a mission is largely unused. Do something with it or get rid of it.
- Less characters that are each more impactful. So many characters come and go throughout the story that I forget who most of them are, especially considering I'm only really fighting with my own creations. It's great that people change sides and all that, but I think there would be some benefit to a smaller, more consistent and more developed party you might actually want to use.