After contemplating for a while, Alex came up with one feasible plan. The start would be the same. However, Alex would summon Leoz, and Fabio around them. They would shout something to make the soldiers panic.
Vera should be able to make a giant ice wall in their right while Greg erected a barrier in their left. That way, they could only think about escaping from two directions. Anna, Jeanne, and Anya should be able to fight with them from the front. Alex, Fabio, Leoz, and Nelson then started killing them from the center.
Without their leader, the soldiers should start running for their life. At that time, they could start chipping their number bit by bit until they killed all of them. Since there was no tree or whatsoever, they did not have any place to hide, so Alex did not need to care about the possibility of missing someone.