Complex sentence: Detective Chimp though tells him that he's a good cop and that they need him to help take down Superman, but before Harvey makes his decision, The Spectre bursts through the door and kills Harvey by obliterating him and his skeletal remains.
Split into simpler sentences: Detective Chimp though tells him that he's a good cop and that they need him to help take down Superman. But, before Harvey makes his decision, The Spectre bursts through the door and kills Harvey by obliterating him and his skeletal remains.