Inferno tactics.

I apologize for asking, but can anyone tell me how to get the max
Dragon Utopia as Inferno?

if you play well, then with a strong stack of demons raised thanks to demonology (dragons are terrified of them). if not so much—then the standard: efreets, devils, angels, vivs + whatever else you find + fodder for health absorption

Added after 1 minute

Does anyone take pits into the Dragon Utopia?
If so, how do you manage to keep them safe?

in my opinion, it's better not to take them. dragons will almost certainly target them.