For me, my favorite villians are the ones that fall into that percentage as defined in the DMG as "Someone in the party is going to die." PC's need to know when they are outclassed and under equipped when that encounter with the villian comes. As a DM, if a PC decides to "Go for it", even though they have been given all the signs and portents that they should not push an issue with a villian at the time and better come back for the encounter later when they are better equipped and matched to the catagory as defined in the DMG that the villian is an equal match, I have no problem as a DM just killing the PC and telling the player "I tried to tell you." As a player, I don't let myself be influenced by the rest of the party in the arene of "Come on, we can do it." I want my character to live, advance in level and gain treasure. I find no amusement at all in playing in games with DM's that by all outward appearances talk about killing off the party slowly and how much fun they will have doing it. To me, thats NOT D&D. Characters are Heroes, slightly better than everyone else, and the purpose of a campaign and adventures is for the PC to be challanged, damaged, POSSIBLY killed if they act stupidly. Mostly for the Player to escape reality for a while, have fun, meet new people and look forward to the next adventure.