To solve this room, the flame has to kill all monsters.
Start by removing these 2 blocks.
But not the ones next to them.

Make a path for the flame.
So that the flame touches all monsters.
The flame must also reach the ice blocks
blocking the way to the purple teleport.

Go to the left and use the key block.
The rest of the room should be easy.

The flame has to kill all monsters.
When it's at the position in the picture
destroy all cyan blocks with the star switch.
This way the flame will fly up and melt
the ice block containing the mystery.