It would be great if one of the strong players shared how to take Utopia on the 2nd week, what skills, units, setup, layout, etc., to use, with Necropolis or another faction.

You need to dig deeper and not be lazy. There is information about your question on this forum.

I can repeat it with Necropolis on the second week.
Galtan with 500 warrior skeletons. Advanced Haste on skeletons or Shield of Skin. The rest of the stacks are decoys. We put them in the 1st stack. With Haste, they will be faster than the right-hand dragons, and Shield of Skin will strengthen them. The dragons will not attack the skeletons if there is a living decoy. If they don't start playing for a victory. For example, maxed Utopia, and you have a weak hero.
It is also possible to have Undead Regeneration, which simplifies the task.