I’ve started running Curse of Strahd and have been having a ton of fun making wacky homebrew things for my party and tweaking the module. Unbeknownst to the players so far, I have made them all a secret Dark Power trying to use them to usurp Strahd and Vampyr, and they’re just waiting to offer their dark gift.
For example, I have a druid with some fire giant ancestry who loves Produce Flame and is their front line, so he’ll be offered a slightly weaker Rage with the Path of the Storm Herald desert feature to use once per long rest. The celestial warlock would get charges to boost his Eldritch Blast damage and some secondary healing in exchange for sapping his life.
Giving my players powerful upgrades alongside typical class advancement can make some encounters harder to balance around, but as long as we’re all having fun who cares about balance??
DM here. The biggest thing for me is when the players get emotionally engaged to the story and the beats. They fell actual hatred for the BBEG. They get so excited about a reveal that they all can’t talk for a minute. Something happens in game, and half the players are having a chat in the Discord in character, outside of game time. The reactions from the players are so rewarding.
The next best is when they come up with a solution to a problem in the game that I hadn’t even considered. It’s kind of fun to have to just say “OK. Hang on a minute. I was totally not prepared for y’all to try that, so I’m going to need to figure out what they impact of that is.” The players always get really excited about that; I think they love to stump me.