Southron Champion
The Sands of Harad #40 (x1)

When Revealed: Discard cards from the encounter deck until a Harad enemy is discarded. Add that enemy to the staging area and place a resource token on it. That enemy is "the Champion." While this stage is in play, the Champion gets +2 Threat +2 Attack +2 Defense and gains: Immune to player card effects. The main quest stage cannot be defeated while the Champion is in play."

The champion cannot take damage unless there are at least 4 progress tokens here. This stage cannot be defeated while the champion is in play.