Mistakes when playing as Humans.

You're wrong, Mент. How will you clear out neutral creatures on adjacent territories? With machines or something? Or will you spend money buying random units? By the time you get there, there will be nothing left of you.

a single ballista is worth a lot at a high-level hero

And how many will it kill? Vitya is probably the weakest machine operator, useful at the beginning, but completely useless in the endgame. A tent is at least useful because it can remove blindness or dispel, but a ballista... pff.