1 - Path
2 - Warning Stone
If you walk past the stones without sneaking, six greater demons will appear and attack you. However, the demons aren't that powerful, so you don't have to worry about being a thief to get the ruby in the altar (#3).
3 - Altar
It contains the Great Ruby of K'alru, the ruby that Gildor Nightwalk of Stillwater wants.
4 - Dead Elf Noble
She's wearing arcane gauntlets and hexed hero's weakness barbarian armor. Nothing happens if you try to conjure her spirit.