My abyss lord and EV2 can see the Rapid Fire large sphere but Mystic can't, I don´t know about others that cost 125k because I don't have them, but the one that increases atk speed by chance when a tower hit isn't showing in my spheres options.
Yeah not all of the heroes can use those particular 2 skill spheres. But it is a little weird only some of the newer heroes can. So I spoke to one of the designers and we can add it on. Lower priority but we'll get them added to the heroes who can't use them.
It´s Panic Fire and Press Your Lucky