Warlock – “Clan Leader” [Campaign 4, Mission 1]

Hmm, guys, I'm new here, although I've been reading the forum for a while – mostly to figure out how to best complete certain missions. I used to play Heroes 3, but when Heroes 5 came out, I switched to it. I completed the "Warrior" difficulty from start to finish. Now I'm replaying on "Veteran" difficulty. I completed the first two Campaigns without any problems, including those where I used to struggle (e.g., "Conquest" for Agrael). I decided to skip the third Campaign because I don't really like playing as Necromancers. So, I started the Campaign for the Necromancer – the first mission. And while there were absolutely no problems on "Warrior" difficulty, it wasn't so easy on "Veteran"! Although I leveled up Raileigh to level 11, his army was significantly depleted after quite bloody battles by the beginning of the tournament (and, as usual, I was short on money). But that's not all. The most surprising thing is that the green player in the game managed to level up to level 21!!! I still don't understand if this really happened within 30 days or if it was like that from the beginning, but we clearly weren't on equal footing at the start. As a result, this green player easily defeated me, and it didn't matter where I was. If I was near the resource, he would immediately attack me, and if I tried to run away from him, he would fight the others, defeating them easily, and it seemed like he wasn't losing any troops at all. Because, quantitatively (and in terms of units), his troops seemed to be the same, whether he attacked me directly or after fighting three other players. I will replay it, of course. It seems like I made a strategic mistake in my development, but still, level 21 in the first mission is kind of strange....