Complex sentence: Whereas the "pre-Crisis" version was a woman in a cheetah-like costume; a more mystical note was added as the character would actually morph into a powerful cat-human hybrid with superhuman abilities, making her a challenging opponent to Wonder Woman.
Split into simpler sentences: Whereas the "pre-Crisis" version was a woman in a cheetah-like costume, a mystical element was now added to the character. Now, she would actually change into a powerful cat-human hybrid with superhuman abilities, making her a challenging opponent for Wonder Woman.