Sounds pretty ambitious... what is your expertise, such as coding, art, audio? This looks like a medium to large team will be needed.
Also there are some issues within your concept... in fact it is not very detailed at all, more like a list of advertisements and very generalized features. For example:
Battles take place on a hex or square grid
Well which one is it? A detailed concept should have this decided.
Players summon from over 100 unique heroes, including knights, mages, beastfolk, dragonslayers, and mythical creatures. Each hero has their own class, detailed skill trees, and evolution paths (e.g., Knight → Paladin or Dark Knight). Affinity system builds relationships between heroes, unlocking team buffs and special story interactions.
Woah, over 100 heroes, with their own skill tree, and relationships between them? Special story interactions? (not just story for each individual?) That's a huge project by itself. Later in the document you mention at Beta time you'll have ~30 heroes which will supposedly take 9 months. Chances are it will take longer, but even so, that sort of means 100 heroes will take about 30 months.
Frequent live events with special bosses, limited-time heroes, and story chapters.
Fully voiced dialogues for main characters and important story scenes, supporting multiple languages
Sounding more and more ambitious here. Voice acting in one language is a big deal. And live events... well, you're going to need staff to support that every month.