Fusion

However, when a source beast master was fighting two against one, it would become the source beast's weakness. It might not necessarily be when two weaker source beast masters were fighting against a stronger source beast master.

As long as the weaker source beast master had his own source beast hold off the opponent's source beast, then the other source beast would be able to order his source beast to bypass the opponent's source beast and launch a sneak attack on him. This way, the source beast master would easily lose his life, and he would definitely be on the spot. There would be no one who would care about justice and carry out a one-on-one mission.