When it comes to synonyms for "sets upon," there is no shortage of options. Some possible alternatives might include "attacks," "assaults," "ambushes," "charges," or "strikes." Each of these words conveys a sense of sudden, forceful aggression, and could be especially useful when describing a violent encounter or unexpected assault. Other possible synonyms might include "engages," "confronts," "confronts head-on," or "faces off against." These options could be particularly useful when describing a more deliberate or intentional confrontation, such as a heated argument or a tense negotiation. Ultimately, the best synonym for "sets upon" will depend on the specific context in which it is being used.