Trick as old as the game Wizardry.
It's often better than making them fight their way back up.
DM: OMG! A portal at the bottom of the dungeon leads directly back to the inn! How convenient!
To be fair, I'd be pretty damn skeptical of something that easy. There's always a catch, and I'd bet dollarydoos to hexed donuts that someone in the party arriving at said inn is no longer precisely who they were going into the portal.
The last time I ran a dungeon, it was with old-school dungeon exploration rules: torches that only last an hour, rations, random encounters, and relatively slow movement.
On top of that, the party was being chased by a squad of angry zombie drow. They'd already burned a bunch of resources, and were fairly hurt, so it was a nail biter.
In my head, that goblin is speaking with Homestar Runner's voice.
That's your inner player talking, but we all know that the DM behind the elevator fuckwith move has that goblin chock-fulla StrongBad, instead.
