Warlock – “Expansion” [4th campaign, 2nd mission]

Yuri_G, you can easily find it without a screenshot if you know there's a path. I found this path after taking the castle – I just explored all the passages. One of them led to the mages' treasure. At first, I was happy – I thought I had found another one. But if you want, I can send it to you tomorrow, as my lunch break is over today. Where should I send it? I figured out that only one hero can visit the treasure. If I had known, I wouldn't have taken it with Raileigh. He had nothing to do there. He already had all the chaos and summoning spells (up to level 4). But Shadia could have learned dark magic spells. Is the order the same in the Dragon Utopia? I'm seeing it for the first time.