

Let them look cool.
Too much time is spent working around the players’ abilities to make a fight challenging. Some fights should look hard but have a player ability break them. Let them use the powers they earned.
This slightly ties to the idea that the game is not the players against the DM, it is the players against the world, while the DM narrates.
Level 2 party vs a Smothering Rug. We each went up to it alone, at different times. The last player ran into a side room with no exit, and after a few moments of silence, opened the door to see if it was gone.
Queue the horror movie music.