Walkthroughs for custom maps.

You can simplify your complex setup by merging the Water of Mutare book. You won't have to generate a clone in the guild and level up its wisdom. You'll only need to expert the water. He won't be casting offensive spells in the elementals. But even with a mana ratio of 600 - 600, I'm not sure if it will be enough for both of us and the computer. Though, he might start summoning water elementals :)

It's impossible to simplify; the current solution is a consequence of the fact that with the Water book, the computer will summon, not clone. Although it might be possible, I focused on something else – on the fundamental possibility of defeating the computer with this strategy.
Here, I cheated a bit, setting the computer's advanced wisdom and water expert in the map settings. And I increased the starting spell points – the probability of reaching level 5 is high. I slightly changed the battle tactics, and here's the result. Accordingly, the main idea works; you just need to get there.