@Salfaro
Well, half of it is teamwork ... the rest is both some extra decades in magic research and tactics on the side on the side of Desir team ( a lot of them taugh by Desir himself, as shown in this chapter ) and plain stupid arrogance from the part of the oponent ( that, TBH, could had flattened Desir & Co if it had not severely underestimated them ) ...
But yeah, more realistic than a lot of manga out there indeed ...