Round table

You can't do that – it's a bug! I played against a Bulgarian, and he was running around without an army. I told him it was a bug and that he shouldn't take the last warrior!

It might be a bug in SoD. And even then, the bug is more likely that a hero without an army has the maximum movement speed: 2000 MP without any bonuses. But in TE-full and WoT, there are special buttons for this, and a hero without an army has the minimum movement speed – 1300 MP, so it's a perfectly legitimate tactic. In the light version, as far as I remember, a hero without an army also has 2000 MP, and this kind of speed boost was usually banned in tournaments.