The hero returns.

I finished this mission today. I completed it on "hero" difficulty in 79 days and received the "Thunderstorm" artifact. I developed Chaos and Darkness skills for the main hero, and I won the final battle almost entirely thanks to Chaos, but without Darkness, it would have been impossible to pass the gate with thousands of Ents and hundreds of dragons. I uploaded a replay of the final battle with Faiden; it's interesting that when watching the replay, the game glitches again and incorrectly shows the regeneration of Fury health due to vampirism – at the end of the battle, they fully recovered, so I completed the battle without losses, except for half of the Griffins, which were killed by archers before the battle began.
Regarding the quests, I completed all of them except for the Sphinx's riddle – I simply didn't have enough time to solve it – I played for less than 4 months.
Regarding the reinforcements that come to the Elves – the humans were completely useless – I defeated them with Sigrif's companion without any losses using 20 Griffins. As for the other reinforcements, I don't know – they didn't have time to arrive :smile53:

P.S. Question for the author: how many bonuses should the ring you receive from Ellaia before the final battles provide? A lot for each attribute, or just one (or does it somehow depend on the hero chosen for the final mission)? I completed the game in both cases, but in the second case, there were more problems – I had to involve Leto and harass Faiden with him for 2 weeks; luckily, after two encounters with Leto in one day, he takes a break and doesn't risk attacking the main hero.

And what determines what percentage of the army the gate should kill?

P.S.S. I think that, in principle, knowing the map and the scenario, and avoiding minor tactical errors, you could reduce the time by a week, but that's probably for another lifetime :)