Lethal Combat
I should confess that I have a reputation for lethal combats. Some of my players even joke that I am trying to kill them their characters, and they’re not entirely wrong.
I spent two years running weekly games (biweekly in person and biweekly online) for Adventurers League. That style of play focuses almost exclusively on one-shots; but if a character dies during a session, then they can bring that same character back to play the next session. (Those characters merely don’t level-up or receive other rewards from the session.)
Prior to Adventurer’s League, I was playing earlier editions of Dungeons & Dragons, during which time characters were more likely to die than survive.
In other words, I’m not shy about character death. I roll in the open, and I let the dice fall where they may. I tune most of my encounters to demand the full attention of my players.
On a personal level, I’m not adversarial. I’m rooting for the player characters in my games, and I want all of my players to have fun; but it’s also true that I take the mechanics of the game engine at face value, and I do not pull any mechanical punches.
All of that said, I do have a house rule regarding character death during level one and level two : If a combat results in a TPK, or if the party does not have the resources to save an unconscious PC at the end of combat, then either the PC stabilize at 0 hp for 1d4 hours, or in the case of a TPK, the party is either looted and left for dead (to recover later on their own in 1d4 hours) or both looted and taken as prisoners. This house rule safeguards characters against squishiness during the first and second levels, but those guard rails are removed starting at third level.