Tower tactics.

Yes - Beast monsters... That's exactly why the Stronghold is a Stronghold. The ability to clear almost all mines by day 3-4 of the first week and, with some luck, overwhelm someone... that's really cool. And the map size doesn't change things that much, except that on L and XL maps, you're unlikely to overwhelm anyone. The only drawback is the upgrade cost - 20 crystals in the first week, and that's just for one building - that's a lot, and if you're unlucky with the resources around you, the tactic will fail. But in Heroes of Might and Magic III, this is the most overpowered and unbeatable faction...