The described tactic was used by the best players on our forum when completing the 7th stage of the Van Cunningham tournament. It was an edited version of the well-known map Beltway. Of course, the gargoyles must be within range of the stompers; only then will they return to their positions. The centaurs are not taken from a single hero; they usually receive assistance from other units (for example, orcs in the case of a barbarian hero).
By the way, if the AI cannot reach any unit within one turn, it will run to the archers, then to the FOOTMEN!!, and only after that - to the flyers.

Орден Феникса – харизматический :) лидер