Mastermind / Jason Wyngarde of the Brotherhood of Mutants.
I plan to intersperse my X-Men uniform design variations with some for the Brotherhood of Mutants. Their uniform variations are going to be less function-driven and more personal-taste, but still working with variations on a theme.
His illusion powers are making his uniform appear shinier, his abs more defined, and his face more conventionally attractive. I tried to symbolize his illusory powers with the whispy "ghost" of his actual appearance. I've toyed with the idea that he, at some point, makes an arrangement of some kind with the Morlock Masque to alter his appearance so that he actually looks like his favored illusory appearance (you know, in my head-canon).
The gratuitous amount of bare skin is deliberate; he used sexual attraction as a weapon of corruption against Jean Grey in the Dark Phoenix story line; his daughter Regan (Lady Mastermind) also had (has?) a similarly-provocative costume, which makes this something of a retcon in a sense (with the idea that she took her inspiration from her father).