I dunno, that seems kinda elaborate. Couldn't he just funnel shumkers to Jetstone instead, or alternately amass a bat/warlord swarm so large it blots out the sun and send it in?
it didnt work for the persians, so it wont work for TV. you do that, and your going to get 300 men in underwear that will slaughter you!
Bats can fly over a phalanx, under the shields [assuming round shields in any position or square held off the ground], between the legs, and through the gaps in columns or rows. A formation tight enough to hamper bat flight would have difficulty moving and would not be able to swing or stab effectively with normal weapons except perhaps accidentally injuring each other. When a bat flew into my apartment 2 years ago it was in a confined space with 2 young adult cats long enough for me to get annoyed by the sound of furniture getting knocked over. It was still flying with some damage to the tail webbing. Hitting a bat mid flight with a spear would be harder than catching a fly with chop sticks (a fly gets eaten within seconds if it lands in a room with our cats). If the spear head has an acoustic stealth design so that the bat could not see [hear with sonar] it coming then the hit rate might go up to the odds of hitting the bulls eye of a dart board while wearing a blind fold. They could have trolls manufacture specially designed anti-bat weapons, tennis rackets for example, but we have not seen anyone carrying them yet.
The combat mechanics of erf world make bats much more effective than on earth. Each bat gets all the bonuses from leaders, artifacts, casters, dancing etc. Large numbers of small creatures would deliver more damage in a small area because they can fit in a small area. The advantage that Sparta held over Persia was the ability to fight in a tighter formation. The Greek phalanx delivered more pressure per linear foot of skirmish line. If used correctly a division of bats would have all the advantages of shock troops. A swarm of bats could punch a hole in an enemy line.
A further advantage of bats is that they should work smoothly with most other types of stacks. Archers or double double archers could fire into the fray. Most of the arrows or bolts would miss the bats. An arrow that did hit a bat would not slow down very much and could still deliver damage. A pike block or phalanx could charge the enemy without blocking any bats or injuring them and vis versa. A dozen bats could also hang out on a friendly shield or on a breast plate. Any enemy that got mixed up with the formation would be subjected to attack by dozens of bats from multiple directions. That would be in addition to damage the enemy received from combat with the bat friendly infantry.
The pass at Thermoplai was held for three days by about 7,000 soldiers. Most of them where sent home after 2 days and then 300 Spartans with a little over 1000 other troops delayed the Persians for some of the third day. It might be worth pointing out that the Spartans died quickly when swarmed from multiple directions. The Spartans also wore breast plates in combat. The Persians and Persian allies had much lighter armor. The movie 300 showed the Spartans in tight boxers because the directors decided that mostly naked men thrusting a long shaft would be hawt stuff. The movie was not an attempt at recreating historical combat. I do not think synthetic fabric was available in 480 BC.