First experience as a DM, I'd like to take a party of level 3 characters to a quick journey to Sigil. What sort of creatures might work at a brewery within the City of Doors?

I admittedly don't know about Sigil, so I'm not sure if this is on flavor or not.. But what about Kobolds?

Typically Kobolds work in the presence of dragons, and perhaps this particular brewery is owned and run by a dragon, who uses it's flame to boil the mash... Employing Kobolds to monitor fermentation (some type of fungus creature may also be interesting) and handle bottling and what not.

Since the players are only level 3, this could be a fun set up for a later adventure. The dragon is out of the brewery.. Perhaps making deals to sell it's brew or gathering exotic hops that only grow on a far away plane... The players come in, kill the staff, ransack the place, drink the ale and the dragon comes back to it's business in shambles. They've made a very powerful enemy who will maybe make an appearance in a few more levels looking for revenge.

Also, the only name I could come up with was I the Dragon's Lager.. Which is supposed to be a play on Lair, but I feel like it's not close enough to work.

Hmm... with the flavor of Sigil I'd imagine the brewing industry to be very competitive. Maybe something addictive due to additives extracted from certain types of creatures is added? Think Slurm from Futurama and run with the kind of creatures that not only would produce the substance, but what would guard them as well. It could also just be a band of creatures or a clan that has access to addictive substances as it's incredibly easy to transport it in through the many portals of the city.

The business could be very lucrative and highly valuable treasures could be contained within and that would be your players goal.

I hope this helps. I don't want to get to terribly specific as there are a lot of options for creatures of this sort. I had just hoped an idea would help you narrow down your research and find something that fits your taste. If you can't decide on something, I can make some suggestions.

Ah Sigil, the city of 1000 doors. I strongly recommend using a d4 to keep the tension high. What I mean is, anytime they start a new 'encounter' (not just combat, but they're doing a thing), toss a d4 that they can see. They have that many rounds before a complication arises (patrol, laser defense grid activates, their source of light flickers and dies, anything that ratchets up the feeling stuff is about to go wrong). Super helpful to keep them moving and thinking, they can't sit around and game out the optimal solution to every problem.

For example:

• A gigantic tankard made for a giant rests above a trapdoor. A DC 15 Str check can move it, or they can lighten it by drinking the foul swill within. A clockwork oni patrols the halls, slow but steady. In 2d4 rounds the guardian will reach them.

• The level they need to get to has one entrance that is heavily guarded and fortified, but the vast network of pipes that run around the facility can be used to bypass this. In order to crawl through one, they need to flush it and open the entry from the brewing chamber. In the brewing chamber are huge vats surrounded by veritable hills of grain, and the whole place smells like a cheap bar the morning after a long party. The massive wheel that flushes the pipe and opens the hatch is easy enough to find, but will take some time to open. As it does, it emits a teeth grating whine as it turns, attracting the attention of the yeast golems and swarms of rats that have made their home in the grain piles. The mechanism once started will continue to work until the hatch pops open. This will take 1d4 + 4 rounds. Each round add 1d4 more monsters to the mix, this being a test of survival not outright killing. Recommend using mob rules, where each member of a mob has 1hp, and instead of each one attacking they give +1 bonus to the attacking creature per member of the mob (ie 3 rats are attacking the paladin, only one actually attacks but has a +2 bonus to hit and damage).

• A very lost and and very drunk dwarf patron has been haplessly wandering the halls, avoiding the dangers with a mr Magoo like luck. He'll give them one of his dwarven trinkets (pick a decent magic item) if they can guide him back to a source of ale. While he's never in danger, his escort will be in the wake of the chaos he seems to usher around him. Crates fall requiring dex saves, he staggers over a narrow railing connecting two platforms requiring an acrobatics check. A moment after he wanders through a cargo door it begins to close, requiring strength to keep it open so the rest can get through.

Awesome! DM'ing is a lot easier than it might seem. Your adventure sounds like a great idea. You might find a lot of inspiration from the module, Barkeep on the Borderlands.

A ton of fantastic TTRPG writers and designers contributed to it. The adventure recently completed Kickstarter fulfillment.

If you're looking for any other advice, just let me know!

Sentient yeast cloud?

Spiders?