Walkthroughs for custom maps.

Neither hydras nor wyverns will attack, as they will take more health damage from the fire than the health of the enemies they kill. Therefore, they wait for the wall of fire to subside. In such cases, a bug occurs where units that are immune to the wall of fire (for example, azure or black dragons) behave similarly.

Added after 13 minutes
It is best to use weak units for the units behind the wall. The computer will sometimes still target angels.