Shadow rine guide of the temple basement.
Note this guide contains spoilers, read at your own risk.
This dungeon is very hard and the first time I played it, I spent quite a few hours going in circles and I only managed to get through because I was following a Youtube playthrough.
So, I decided to make this guide in the hope that someone would find it useful. It is very hard to follow what a person is doing by just watching a video, so I decided to make a text guide where I can exactly describe what I was doing.

first floor

you start out in a room in which you can either go north or south.
go north from here.
you are now in a room, in which there is a chest surrounded by a wall. I will call this the main room for the first floor.
this room has 4 exits. go east from here.
there are 3 exits from this room
go south from here into a room which has a chest in it
inside the chest there is the flame key.
Pick it up an go back into the main room.
from here go west
go north from this room through the flame door into a room where you will find the water key
to get the water key you have to go west, north and east and jump over the pit.
note that since the pit is right on a drop off you will not get the edge warning.
go back to the main room and go east
this time go north through the water door
then go east down the stairs to the second floor

you start out in a room in which you can either go north or south.
go north from here.
you are now in a room in which there is a chest surrounded by a wall. I will call this the main room for the first floor.
this room has 4 exits. go east from here.
there are 3 exits from this room
go south from here into a room which has a chest in it
inside the chest there is the flame key.
Pick it up an go back into the main room.
from here go west
go north from this room through the flame door into a room where you will find the water key
to get the water key you have to go west, north and east and jump over the pit.
note that since the pit is right on a drop off you will not get the edge warning.
go back to the main room and go east
this time go north through the water door
then go east down the stairs to the second floor

second floor

this is the second floor and is a lot harder.
go west into a room which has a checkpoint. I will call this the main room for the second floor.
from here go south.
go south again.
go east into a room with the wind key. this room is tricky because you have to do some platforming to get to this chest.
go south from where you came in then go east all the way, go north all the way
go east all the way. then go south until you can go east. go east then go north and jump over the pit and go east then go north until you see a drop off to the east and the west. go west and get the key.
go back to the room south of the main room and this time go west through the wind door.
this room has 4 chests.
the bottom left chest steals 50 curin. the bottom right chest explodes and hurts you a lot.
the top left chest contains the earth key
and the top right chest teliports you back to the temple.
take the key and go all the way back to the main room of the first floor and go north through the earth door.
in this room you will find the thunder key.
now go all the way back to the main room of the second floor and go through the thunder door.
you will find the ice key.
go back to the main room of the second floor and go west through the ice door.
go west down to the third floor.

third floor

go south into a room with a checkpoint.
now go east into a room with teleporters. warp east into a room with 3 exits to the north. I will call this the main room of the third floor.
this room is very confusing because the 3 exits are very close to each other and look identical.
go north right as you enter.
in this room there is a chest with the tree key inside it.
take it and go back into the main room  and go through the right most exit
follow this room north, east and south.
in this room there are 3 exits to the south.
take the right one and go through the tree door.
in this room you will find the rock key. take it and go back to the main room.
go through the middle exit and go north, east and south into a room with the rock door.
go through it into a room with the light key.
take it and go back into the room with the rock key and go north, west and south into a room with the light door.
go through it and flip the switch.
go back to the room with 3 exits to the south. go through the right northern exit and get the empty key.
go back to the west entrance of the teleporting room and warp south.
go south through the empty door and up the stairs.
there are 2 chests here one of them contains the darkness key and the other contains 50 curin. open both and go all the way to the main room of the first floor.
go through the west door and then south through the darkness door.
fall off all the drop offs and then go through the north door.
go north again and then go through the east door and flip the switch.
now go all the way back to the main room of the first floor and the wall surrounding the chest will disappear. note you sometimes have to walk around the wall a little before it disappears.
in this chest there is the boss key.
now that you have the boss key you have to go back to the main room of the third floor.
go west into the teleporting room. warp west once then go north into the boss room.

the dark orb

as you have heard in the story you can not attack the dark orb.
the dark orb can not attack you directly but will generate enemies.

how to defeat the dark orb

to defeat the dark orb you have to knock it into the pit.
how ever you have to hit it when it is not about to generate monsters and when there are no monsters on the field.
how do I know when it is about to generate monsters, you ask?
when the battle starts you hear the dark orb growling.
this means that it is about to generate monsters.
the first time it generates a lot of monsters and after that it generates one monster at a time.
each time you knock it into a pit it loses some health and the cycle starts again.
the number of times you have to knock it into a pit changes for each difficulty.

List of where to find all the doors

Note this is a rough guide and if you want details please look at my main guide above.
Door    floor    Location
Flame door    1    North west of the main room
Water door    1    North east of the main room
Wind door            2    South west of the main room
Thunder door    2    South of the main room
Earth door            1    North of the main room
Ice door            2    West of the main room
Tree door            3    North of the main room
Rock door            3    North of the main room
Light door            3    North of the main room
Empty door    3    South west of the main room
Darkness door    1    South west of the main room