ToEE: Lower Temple Complex

Air Temple
Head west and enter the door marked "To the Western Halls & Air Temple quarters". Head south, kill Kelno and disable the air rune. Head back to the central hall, drop down and take the Air Temple Key. Use the air jets to go back up and head south to find the Water and Fire temples.

Fire Temple
There are pressure plate traps in the hallway leading to the fire temple. Make an offering to obtain the Fire Temple Key. Anything lower than 25,000 platinum will trigger a difficult fight with all the clerics and two orange named Fire Salamanders.

Water Temple
Get water from the fountain and fill the altar to remove the barrier. Head south and take the water temple key, this will cause a red named Living Pool to spawn, which is a Gelatinous Cube that deals acid damage. It also paralyzes on touch with a very high fort save. The pool is immune to electricity. After defeating the pool, you will have to defeat two red named water elementals in the side rooms to leave the temple. You can skip the fight using Dimension Door.

Go back to the water temple and enter the "Western Halls and Dungeon Level 3". Head SW till you find the elemental barriers, unlock them and head down to level 3.

Level 3
Head east, then north from the shrine to find Falrinth's chambers. He will summon three orange named elementals to attack you, they are immune to damage while standing in the area of their own element. After defeating them, he will summon a orange named Bebilith and start attacking you with spells. A ranged weapon is necessary to kill him. Head past him, read his journal and pick up the Orb and Mysterious Page. Enter the blue door that appears, head south and place the orb on the pedestral.