To battle Strahd in a single night, all you need is a copy of Curse of Strahd and 3 to 6 friends to play with. I’ll include the changes and optional rules I use to run Ravenloft as a one-shot adventure, but feel free to mix and match these rules to suit your table.
You will have to make a few changes in order for the characters to fight Strahd before the night ends or people get exhausted. Ravenloft is a large place, and exploring it thoroughly isn’t really possible in a single sitting. This means that, instead of preparing all of Curse of Strahd, you will only need to prepare Fortunes of Ravenloft from chapter 1 and Castle Ravenloft from chapter 4 of the adventure. Your goal is to create a scenario in which it’s possible for the heroes to kill Strahd von Zarovich in a single session of play. If you haven’t ever had a D&D Halloween mega-party and battled your way through the halls of Castle Ravenloft with the sole objective of destroying Count Strahd von Zarovich, then you need to wrangle your friends and try it! Have you had your annual Halloween playthrough of Ravenloft yet? It's one of my favorite Halloween traditions. Monstrous Compendium Vol 3: Minecraft Creatures