HL D&D 4.0
Proposed House Rules
Reduce mob health by 25% and increase mob damage by 25%. Start there. If that still isn't good enough, incrementally nudge things up 10% a shot or so.
Skills should be more important. Unfortunately, it doesn't seem like the modules put much effort into putting situations in, so they would have to be tailor-made campaigns probably.
More roleplaying. I don't really know how to make that a house rule, but I don't think there's enough of it.
Saving Throws vs. Effects
With the way things are now, you have a 50% chance to negate some effect placed upon you in one round, and an 87.5% chance to have negated it after three rounds. I don't think it's fair that a Daily power can be so easily negated.
1) The debuffer can maintain the debuff every round as a free action by attempting the attack again. If it succeeds, the debuff remains. If it fails, the debuff goes away.
2) At the time the debuff is applied, the debuffer continues rolling the attack until it fails. The number of successes before a failure determine the length in rounds the debuff remains on the target. In-game, this is kinda like your character knows how hard he hit his target/how strongly he affected his target's mind. This could also be done fairly quickly as well.
3) Duration based upon how much the attack was over the target's defense.