Today in my kids' campaign, they explored the caverns below the goblin caves. At the direction of Larry the Dwarf Cleric, they stayed to the right as they explored, coming across numerous forking passages.
First up, a bunch of piercers fell off the ceiling, attacking them. Most of my attack rolls missed; I was rolling d20s out on the table for each player. The wizard, my 10-year-old son, insisted on rolling a d20 for himself, without realizing I was rolling attacks for the monsters.
He rolled a natural 20. We spent the next five minutes as we both rolled low, him trying to knock the piercer off, and the piercer failing utterly to chew through the wizard's robes. He finally knocked it off with his staff and they avoided the rest of the piercers on the ceiling, and went into the next room, where they barely managed to avoid being caught in the filament-traps of a group of three cave fishers! This combat went quickly, although it seems the only time I roll criticals for monsters is when the wizard gets too close to combat and a monster snaps at him!
They defeated the cave fishers and continued on, keeping ever to the right. The next foe they encountered was a big nasty roper. The roper snagged three of the heroes off the start with its tentacles, and started pulling them in, but they managed to make excellent attack rolls to slice through the tentacles and break free. They had to gang up on it, and nearly lost Snagger the Dwarf, but defeated the monstrosity and found the gems and platinum pieces in the roper's belly.
They continued on around the map, and came to a maze-like series of passages. It wasn't long before they were attacked from two sides by some big subterranean lizards! And then a few rounds into the fight, two more joined the fray, led by their minotaur master! The fight was looking kind of grim when the minotaur showed up; the wizard dropped (lizard got a crit for 12), and Farmer George wasn't far behind. The minotaur circled around and charged the halfling thief, but rolled a two; I ruled the thief tumbled between the minotaur's legs and popped up behind it, granting her a backstab attack for extra damage. The two elves hit, with the first hit being a "ghetto crit" for maximum damage and the second elf scoring a natural 20! The 6+3 HD minotaur went down quick, and its pet lizards weren't far behind.
After taking a few minutes to heal up, they continued on their path, ever to the right passageway, circling around the map. In the next chamber they encountered an Auromvorax! Since the book states that dwarves despise them, I gave each dwarf a roll to recognize the beast. Snagger made his roll, and knew that the monster literally eats gold for dinner. They started throwing gold pieces at it, enough to distract it for long enough to get by.
This is when they started discovering the remains of a group of adventurers who hadn't survived the dungeon. They recovered a spellbook with high-level spells and a tube of scrolls containing several sheets worth of bad poetry.
Having gone most of the way around the dungeon, they headed back up to the goblin lair and made camp for the night to rest up. Nothing attacked them in the night (the goblins had left, most being cowardly and having no desire to be around when the group opened the passageway down into the deadly caves).
Further exploration the next morning revealed a hidden, ancient dwarven crypt. The dwarf cleric opened the passageway and down they went, finding a 1000-year-old internment containing several generations worth of urns and an altar, with a blessed dwarven warhammer floating above it. After saying a prayer to Moradin, the dwarf cleric took the warhammer.