I apologize for the inadequate replay. After testing the tactic on 3 stacks of 60 warlords each, it proved effective. Indeed, it's an excellent tactic for the Orc, but the Knight can still win by using Subjugation. However, the problem is that, as Mdance correctly pointed out, the Orcish invasion won't end there, because there are still Warmongers, Paoka, and Centaurs. By that time, the Knight will have at most a couple of surviving stacks (at least, according to the results of my battle; I won't post the replay this time). Nevertheless, there are many questions about the tactic, such as the hero's skills must be at a decent level, and there should be several secondary skills, and the game should be played exclusively for a long late game. But what if, for example, the Knight decides to stay in the castle?
P.S. Here's another thought. What if the Knight has Shackles and defeats the Orc with Cyclops? Then the main hero is lost, and the remaining Orcish stacks can be dealt with even with what the Knight has left, if he has Vampirism and Subjugation.