Unstoppable
Fighter Utility 2
You let your adrenaline surge carry you through the battle.
Personal
Effect: You gain temporary hit points equal to 2d6 + your Constitution modifier.
Unstoppable 
is a second-level fighter utility power, best suited for Fighters with a high constitution score.[PH:78]
It is a poor choice. Despite giving out a good amount of temporary hit points at level 2, it is only once per day, and doesn't scale to higher levels.
Errata
- The power was modified in the Class Compendium, removing the Healing keyword. This change isn't recorded in official errata.