The session went really well on Sunday. Here's how it went down.
The scene was set with Mach Ten faced off against Nightshade, with about half a dozen minions scattered around on rooftops. Mach got initiative (naturally) and the player decided Mach's hatred overcame common sense and he charged her. She took the blow unfazed, then brought down the darkness (Obscure) and stepped back, Taunting him about the death of his parents. The minions then opened fire, but missed. Mach knew he had to get out of the darness radius, so he decided to just try running in a straight line. But Blinded and on unfamiliar territory, he misjudged his line (botched INT check) and ran into an obstacle. Nightshade then used her used her Turnabout teleport stunt to hit Mach for a Drain attack, dropping his DEX by 8 points. Combined with the blindness, this knocked his defence down enough for the next Minion volley to score a couple of hits, one of which put him out.
So I got my scene with Mach trussed up like a turkey, and managed to spill a little of the metaplot to him. Job done. When the cavalry arrived and Mach Ten broke loose, Nightshade used the same tactics to great effect, getting Mach down to DEX 2, and tagging the team's Brick and Psychic with a well timed Fusillade attack. In the end those two took her down with a great bit of teamwork, the Psychic locking on to her telepathically and downloading her location to the Brick via Group Link. Next time she 'ported in for a surprise attack... BAM!
And I have to give credit to my players, they deliberately gave me an opening for her to escape at the end of the session. They had her tied up in an alleyway, fully illuminated by a truck's headlights to prevent her from using the shadow teleport. When Mach Ten and another character started interrogating her a little too forcefully, the Brick felt obliged to stop them, so he reached across to pull them off, casting a shadow large enough for her to use, and with a wink...she was gone. Although I felt a little guilty about robbing them of the capture, everyone thought it was a great ending. I guess I'm lucky that my players really get the comic book idiom.
Thanks again to everyone who came up with ideas. I now have a pretty cool recurring villainess who can give the heroes a run for their money. And I must have Mach's player scared, as the first thing he did with his PP reward was invest in a pair of Darkvision goggles