So, while player rush to pick up Cyclops and Xavier, I randomly came across the fact that SSR She-Hulk+ actually appears to proc a huge bonus. Not quite a thousand but over 500% is what I've seen. Its definitely not the boost for bruisers since both Havok and She-Hulk are bruisers but she does close to triple his damage.
I don't know if this is working as intended, or it's a glitch that will be remedied. I have heard that one of the Hawkeye cards also has a boost, but I haven't been able to verify it.
Since Havoks boost is less than expected, and Phoenix Force isn't offering one (despite that 'future event' text I saw) I'm fairly pleased with the fact that She-Hulk is offering a nice big boost.
Maybe not as secret as I thought. I have no idea where this picture was taken from because I've looked all over the page to find it. Thanks to Sean below for linking it. Either way, the boost seems to be pretty heavy on She-Hulk.