Is there a list of characters that reduce AP for team mates like IWBW Brush pass?
Shuri, 4* Starlord, Hellcat. That’s all that comes to my mind immediately.
4* BW yellow is another.
there’s a few characters that can lower their own costs. 4Ghost rider, Spider-Gwen (depending on web tiles) are two I can think of..
Venom (Eddie Brock) green
Quicksilver has self reduction
Then there’s also conditional free powers - Mockingbird, Mr. F
alternatively you can raise opponent cost on powers. Shuri/Peggy are a great combo for that, since Shuri simultaneously reduces team cost, and the AP tax stacks up to 7 between them.
Note that 4* Ghost rider (and similar) have a hard minimum on how low they can go, and it isn’t the default 3ap minimum - whatever it lists in the power is as low as you can take it. So for Ghost Rider, you can use a cost reducer like shuri to get it down to whatever the stated minimum is, but having N attack tiles in play won’t take it any lower than that.