Archidon massing isn't a very good strategy in my opinion, like all massing (unless it's albowtross, which only needs a good meat shield to protect it from castle archers). All units have weaknesses, and the Archidon is weak against Albowtross, Speartons (unless they have other tanking units), and Magikill (lol Magikill Wall will destroy everything, unless the opponent can micro excellently and is clever against mages). However, Archidons make a good combo with other units, such as Speartons, Giants (not the best, but ok), and pretty much all melee tanking units. Plus, Archidon massing is not good for offense. If the opponent has even ONE castle archer, and you attack with an Archidon mass, boom, you lose. I'd say that 6~12 Archidons would work well, depending on the situation.