[Ironhawk]

Generally speaking, the early and mid game are the only times where hordes of troops will benefit you. Even if you pursue a land-denial strategy as you appear to outline in your post. Eventually, a skilled opponent will simply start fielding stuff that literally cannot be beaten by any size of mortal army. The most common of these tactics are the anti-personnel SC and the battlefield-wide damage enchantments. Once these strategies become available in the mid-late game, large groups of unsupported mortal armies actually become a liability.

As for your Dragon army: they would probably be pretty effective vs human troops, but in the grand scheme of things its a criminal waste of gems. A single large SC with a moon blade or a handful of properly protected mages casting Opposition or Control could defeat that army pretty easily.