-You can acquire many useful spells in the library if you develop the hero correctly.
-You can complete the Prophet’s quest and build two Academy cities, but you need to deal with the Death’s assistants first.
In my opinion, it’s easier to attack the Necromancers – they aren’t particularly strong in attack. All you need is the Sar-Issa Robe and a fireball dealing 3000 damage. Did you unlock the second treasure chamber? With an artifact that provides a bonus to spellcasting?
Added 1 minute ago
By the way, I added a Fire Wave to the boss – the problem is that he doesn’t want to use it…
And also – he’s an elemental, so you wouldn’t have been able to Control him anyway.