In the War of the Ring, when the Fellowship is climbing Mount Doom, does reaching 12 Corruption points mean instant death?

In the decisive battle of *War of the Ring*, Frodo and his companions are climbing the steps of Mount Doom: If, on a single Hunt Tile draw, Corruption plus damage directly reaches 12 points, does the game immediately end with a judgment of a Shadow victory, or is the Fellowship allowed to use a companion sacrifice to offset it?