Black Knight's relative frailty and vulnerability to range keep him in check, but he has decent offensive upside for a figure in his point range. He likes stat boosters as much as anyone, as well as figures like Weather Wizard who can protect him from range until he gets opportunities to attack. Solid Magical Defense assassin, but there's usually more value in just taking a figure with Magical Defense. 3/B
Hellcat doesn't do much. She's a cheap adventurer at least if you for some reason want to run the Fan Four at 800-900 and swap out one of Human Torch or Thing for her and Wasp (I). You get more out of Wasp in that dynamic for 25 points less, though. 2/C-
This seems to be the hate on magic users grouping, with the third that matches up specifically against Magical Defense. Valkyrie gets her real value from her 7 Life, 7 Attack, and Deathglow Perception, though. As long as you can keep her from being Stuck or so forth and keep her podded up and in the mix, she can make it a real pain to take out her team. Pair her with other figures like Jocasta or Avengers Thor to give the opponent a bad time. 4/A
Nobody covered things on Yellowjacket. He's all about offensive output and there are lots of ways to exploit him. Go non-thematic and give him an obsession that's fairly high life to keep triggering the effect. Someone who draws fire (Blob, Valkyrie, etc.) is a good choice for his obsession. 3/A-