Anything more than 8 players is pretty much impossible to run- if NONE of them have played DND before, demo one sessions with a party of eight, or have them tag team. Don't put 15 people and an appropriate number of monsters for them to fight on the field at once, you will be spending half an hour every round of combat, and people will all be vying for the spotlight out of combat. Once they get the ropes, or if some of them have played DND before, get some more of them to DM and have them run their own campaigns.
Since you're with a large group and trying to impress them, you'll want to streamline as much as possible. Pre-roll ALL your treasure, and maybe pre-calculate XP. Have character sheets ready for them to play, even if you intend to have most people build their own. I'd say demo them a dungeon with a short role-playing info, two encounters at their CR, a trap and/or puzzle room, and a boss two or three CRs higher than them*. If you don't intend to keep using the characters from your first session, throw them something really useful they can use at them before they hit the boss, like a powerful magic weapon or staff. I also highly recommend starting them at level 2 or 3, so they can take a few hits. Also, even though you normally never level up in one session, you might want to arbitrarily give them enough XP to level them up once, so they can really feel like they accomplished something in your one demo session.
One setup I did that I thought worked well, was to have the players start in a tavern, and the barkeep asks them to fetch some special wine from the cellar. A will save told players that something was suspicious or illusionary about the tavern. The cellar of course was actually a dungeon, where they fought a bunch of weak zombies as one encounter, a couple barghests (my party was 8 lvl 3 characters) in the next room, and then they entered a treasure room complete with the wine, where a gargoyle attacks them when they take the wine. Upon returning to the "tavern" they find themselves to have been in a mausoleum, and there's a wraith floating over a coffin with the bartender's name on it (make sure to establish the bartender's name). Pouring the wine over the coffin caused the wraith to disappear, or if the party's just jackasses they can fight the wraith.
Another interesting one-off dungeon would be to have the dungeon be a spectator sport where the party races through- which gives you an easy excuse to have arbitrary traps and monsters, as well as go easy on them by having spectators (either through grated windows, or grates above) offer advice, or selling healing potions mid-dungeon. This could also easily allow you to throw in a rival party and establish them as the villains. But the big advantage to this is you can throw in whatever obstacles you want with no rhyme or reason; someone put them there so it would be fun to watch the party go through!
A note on Challenge Ratings: As much as possible, don't try to account for a large party by throwing in harder CRs.
Monsters CRs are designed for a party of 4, so for 8 people, you should try to throw double the number of monsters at them. When you throw one big monster in, it tends to hit one player really hard, and make other players fail to do anything to the monster on their turn and feel useless. I had a DM who did that, and as a cleric, enemies never failed my spell saves so my spells were mostly useless until I got Searing Light. Normally, doubling the number of enemies increases CR by 2, but for a large party, just double them first (or use one enemy and one weaker enemy to one-and-a-half the encounter) Also, as a general rule, encounters with a level equal to the party+4 are exactly as strong as the party- for example, a clone of the party would be a CR four levels higher than the party. Since the party is multiple people, this pretty much means that even in victory some of them are going to die- don't do that to your new players. Typically, a CR+3 is plenty for a "hard" encounter, or a CR+2 if the party has already been through a few encounters.
...well, there's my wall of text, I hope you find it useful.
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Topic: Help me plan an adventure for DnD newbies! (Read 4125 times)