“Kill your darlings” is a great piece of writing advice from various people (including William Faulkner and Stephen King) recommending that you edit out all your most precious turns of phrase, and leave your work stronger.
“Maim your friends” is my personal advice on causing the maximum pain (and, just as importantly, danger of more pain) for your characters. (Sidebar: A couple of writers, like Robin Hobb, take it too far for me to ever re-read them. Most don’t take it far enough.) It hurts to do horrible things to characters you love – but it’s necessary. Plus, it pretty much comes along with the “godlike powers” thing that us writers like so much.
Here‘s one of Chuck Wendig’s delightfully rude and abrasive articles – this time on hurting your precious characters.
And here’s someone who’s an expert at killing and maiming: