I agree with Magicsofa above, this game concept is too ambitious and some lines are unclear, such as these:
Each faction—Kingdom of Virelda, Dominion of Drae, Obsidian Cult, etc.—has unique campaigns and side quests.
Smooth pixel or 2.5D tactical sprites with fluid attack and skill animations reminiscent of Langrisser Mobile.
However the real issue is who is going to make this game? and why are you posting this concept here?