After several evenings of storming the dungeons of The Temple of Elemental Evil we decided to put the module to a rest since not too much happened, as the dungeons were deadly and it kept being supplied by new monsters, forcing the players to deal with areas they had already explored. Instead we decided to play N5 Under Illefarn (1987), which consists of three small introductory adventures and then a huge dwarven mine divided by three factions.
One does not simply walk into the mines of Illefarn. Its dark corridors are patrolled by more than just orcs. There is evil there that does not sleep. The dreadful necromancer and the dwarven prince are ever watchful. It is a barren dungeon, riddled with old traps, new traps, and empty rooms. The water rushing from the mines is a poisonous sludge. Not with ten thousand sessions could you map this. It is folly.
Boromir on exploring the dwarven mines of lost Illefarn.