Was the fiery being in the sarcophagus Brand?

The being I'm talking about is described as "a beast of living fire," "the spirit of eternal fire," (source )) "a magical being of fire," and "the ancient being of fire" (source )).

The old lore describes brand as a column of fire locked up inside a perfect cage of ice before possessing the human explorer. Brand's power to possess a human would explain why Nasus and Renekton had to be sent, instead of normal human soldiers.

Plausible? Half-assed? Completely wrong?