On Sunday, I was running my TS&R game, and the party was exploring more of the mini-mega-dungeon. They were basically looking at their map, and trying to fill in gaps on the 1st level.
The party consists of:
Koles' Human Wu Jen 4 and henchman Holes' Human Wu Jen 1 (my son Flynn's characters)
Citizen Snips Human Blade Mage 4 and henchman Niko Human Fighter 1 (my son Steven's characters)
Fei Mao Crane Hengeyokai Kensei 4 and henchman Snakebite Human Mudang 2 (Denis' characters)
10 Bad Habits Koropokuru Yakuza 4 and henchman Savage Poko Raccoon Dog Hengeyokai Fighter 1 (Justin's characters)
4 Men-at-Arms, wearing leather armor with axes and short bows.
They returned to the Underground Garden and bought some fruits, vegetables, and flowers from the treants that tend the garden. They made peaceful contact with some tengu and got a tip that it might be possible to get some swordsmanship training at the tengu encampment south-west of town (I need to flesh out that spot on the map now!), fought some astral projecting evil spirits called berbalang and got some treasure, discovered a secret door that led to one of the areas they'd explored in the previous sessions where a black bear was snacking on dead goblin rat and giant rat corpses (they used some purchased fruits and flowers to discourage the bear from following as they retreated), and then they came to the first of several locked doors.
10 Bad Habits picked the lock, and there was a short corridor with another door. He was unable to pick this one, so they bashed it in after listening and hearing nothing.
This was a subsection of the level that has been taken over by bandits as their lair. And a random roll showed me that no bandits were in the common area, but that there were 60 bandits plus their leader, a 3rd level Xia (martial artist/monk) in other rooms of the lair. The bandits were in three rooms, 20 per room, and the leader in his quarters.
Bashing the door made noise, but a surprise roll gave the players time to set up their forces. There were four doors into the common area that they could hear unlocking. They arranged their men-at-arms in the center of the room to fire arrows, and each pair of PC and henchman took a different door. Koles' and Holes' weren't next to a door, but they had spells prepared for the door the others hadn't covered.
When the bandits opened their doors, Koles' used phantasmal force to make the floor lava, and after 20 saving throws, all but three thought they were being incinerated and fell unconscious to the floor, as the arrows from the men-at-arms eliminated two more bandits in the 'lava' room.
Holes' turned to use his sleep spell at the southern door where 10 Bad Habits & Poko were waiting, and his sleep spell took out nine more bandits. 10 Bad's backstab missed, unfortunately, as did Poko's attack.
Meanwhile, Fei Mao used his Sweep ability to attack four times against 1HD opponents, and took out three of the 20 in the room he and Snakebite were at, while Snakebite went defense mode to avoid taking massive damage.
Finally, at the leader's door, Niko hit the leader with his magari-yari +1 doing some decent damage, and Snips used cause fear to make him run back into the room and cower.
With their leader running in fear and half their forces eliminated before they knew what was happening, I rolled morale for the bandits and they failed. They surrendered, and were all tied up.
One 4th level party took out an encounter with five times their numbers without taking a scratch. And the bandits had a Type A treasure, which was mostly jewelry and art objects, so it was easy to transport back to town with their captives. The treasure from the berbalangs and the bandits was around 34,000gp, so everyone but the Blade Mage leveled up, and Niko the henchman is 1xp shy of 3rd level due to the rule on gaining only one level per adventure.
And now that they have access to the bandits' secret entrance to the dungeon and that easy to seal off section of the dungeon, the players are thinking to convert that to their dungeon delving base.
This was much more fun and exciting than if it had been a 5E style "balanced encounter" with just a handful of bandits attacking at a time. Oh, and for anyone wondering how fair it would have been if the party had discovered this area while they were 1st level, the bandits aren't killers. They would have used non-lethal attacks, disarms, overbearing, etc. to try and capture the party and demand ransom from town if that had happened. I don't mind it when PCs die in my game, but I'm not out to kill them. That's just too easy.