Ki and Gil will enter this room through the first of the eight doors at the centre of it - and it contains no enemies at all, (unless Will O' Wisps appear).
This room, like the left half of Empty Cistern, wraps around vertically - and if you proceed in either direction, you will end up back where you started.
The key at the left of the room opens the eighth door at the centre of the room, and the third key at centre-left of the room opens the aforementioned first door at the centre of the room. The first and second keys at the centre-left, bottom and bottom-right of the room do not open the other six doors.
The eighth door at the centre of the room leads to Alchemist's Room (Room Pass: 9V7), and the aforementioned first door at the centre of the room leads back to Goblin's Lair (Room Pass: DC2). You should remember the first of these Room Passes, especially as that room contains a bad item...
