The spawns were caught in an ambush and a lot of them died in the initial shock but it doesn't mean that they will just let the wyverns kill them. In fact, it was exactly the opposite thing
Due to the tactic that these wyverns use, it made the spawns' desire to kill them to grow a lot. And since Caizher is doing a good job attracting the enemy's attention, why don't they use this to their advantage?
Caizher gained some breather and his mind starts to work now. He is sure that the spawns already sent signals to the army camp (a.k.a the large towers in the middle of the space) and reinforcements would soon arrive in this place
Caizher needs to work smarter not harder. The most important thing is to survive while making sure that his kill count would rise