Sanctuary of the Flame is a level of Tomb Raider: The Angel of Darkness. It is part of the level The Hall Of Seasons.
As Lara enters the room, a brief cutscene shows a little stream of lava moving through cracks on the tiles further into the room. The the whole place is destroyed by lava and fire as a big wave of fire goes past, turning the liquid in the room into lava and causing fireballs to fly in the room.
It's wise to wait in the doorway until the fire wave has gone past, because if Lara gets hit by the fire wave, it means instant death, as well as falling into the liquid before and after it has turned into lava. After all this, Lara must make her way across the lava by using the small platforms, which start to sink into the lava soon after Lara steps on them.
When on the other side, Lara must take the Fire Crystal and then make her way back to The Hall Of Seasons by using the suddenly appeared mini-platforms.