I'd love to see branching classes beyond the current one to add to the diversity of builds. Maybe have an Good/Neutral/Evil spectrum that can be influenced (to some extent) to add another layer of separation, or more complex buildings that increase X on level up. An Alumni feature. As others have said, a more meaningful story. School-related mechanics, such as Student Councils, Exams, Competitions, Festivals, Student Exchange. Principal's Skill Tree based on Reputation. Stuff like that that allows us to diversify and have a more interesting game.
thank you for your suggestion. Just info, we will made a new game Valthirian Arc, it's called Valthirian Arc: Red Covenant. You can see it on kickstarter. https://www.kickstarter.com/projects/agatestudio/valthirian-arc-red-covenant
The difficulty at higher levels without abusing the AP Boosters for the bosses is absolutely ridiculous. No slay = 15 max AP turns to take the boss down even with Chilli buff (5m MHP). Of course, the fact that they tend to kill you in one turn doesn't help much either. :/
If you even want to THINK about doing the Lv70+ dungeons for the first time, make sure to bring at least 20AP Booster IIIs and an inane number of buff items. Farm the gold in missions "Defeat the Trio Assassins" or "Legendary Silver Wolf II".
Then again, I don't have any ultimate eq, so it may be different then. Either way, without slay weapons that can continually chain (I'm looking at you, greatsword!) and a decent amount of STR, stay away from the high level missions. Most of the time it's easier to just farm up.
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thank you for your suggestion. Just info, we will made a new game Valthirian Arc, it's called Valthirian Arc: Red Covenant. You can see it on kickstarter. https://www.kickstarter.com/projects/agatestudio/valthirian-arc-red-covenant