He keeps a keen eye on the thug engaging him and begins to repeat his spell, although instead of trying to obscure it, he focuses on managing to perform the melody without making any openings on himself. He hopes their alcohol content makes them more susceptible to it, and tries to aim to get as many of the thugs into the spray as possible.
[Color Spray, Defensive Casting (Melodic Casting): 24, DC 16]
(I am not sure if Combat Casting applies if he uses Defensive Casting with Perform via the Melodic Casting feat. If it does, then +4, not that it matters in this situation.)
[Priorities for targeting: Thug #2, Thug #1, Half Orog. If Worgo is required to fall into the area of effect as well to reach them all, so be it.]
(In case he can only put one opponent into the spray, then he’d rather just swing his sword at Thug #2, with the same roll that’d be 21 to hit, or can draw from the pool if that’d need a new one.)