I run a pretty lethal game. Typically, though, I have a large number of players (not so long ago we had the so-called Adventuring Thirty, which actually consisted of somewhere around 15 players, with about half at any given session), and that helps spread the damage out.
I'm not really out to 'get' the pcs, but as they make enemies there are more things that come their way, and the better their enemies know their tactics and abilities, the better they can prepare for the pcs. I don't pull punches and I roll the majority of my dice in front of the players.
I have found that as the party got more powerful I could really take the gloves off. Even so, they tear through enemies of equal CR. But when they get into really nasty scrapes, they know that it
could come to a tpk. The last time I had one was when Tharizdun ate my old campaign world- that would be Greyhawk- in 1993, but we've come close and I've looked it in the face and realized that, if the pcs are stupid and the dice go against 'em
I'll do it.
I rarely fudge dice; I used to do it much more often. Nowadays, I'd say I fudge about, hm, once every 2-4 sessions. I always try to balance it out later- so I might fudge once for the pcs in a really tough fight, then once for the bad guys in an easy fight.
Good thread. We should start some sort of Killer DM Klub.