Complex sentence: As MacReady rushes to set the charges, Blair, now metamorphosed into a larger monster, emerges from below and destroys the detonator, but MacReady still triggers the blast with a stick of dynamite, destroying the abomination and the base.
Split into simpler sentences: As MacReady rushes to set the charges, Blair, now metamorphosed into a larger monster, emerges from below and destroys the detonator. MacReady triggers the blast with a stick of dynamite, destroying the abomination and the base.