Complex sentence: He heeds Jor-El's warning about the imminent destruction of Krypton, but rather than validate Jor-El's claims, he dismisses them as false while secretly working to save himself.
Split into simpler sentences: He heeds Jor-El's warning about the imminent destruction of Krypton. But rather than validate Jor-El's claims, he dismisses them as false while secretly working to save himself.