This ability is given to Christof after navigating Josef's Tunnels, to Pink at the top of the Tower of London, and to Samuel at the end of the New York Sewers. Fortitude, like its fellow physical combat enhancement Celerity, is not given as a Tome in the single player game.
The Fortitude soak is said to be against Aggravated damage. Its damage prevention effects are hard to detect. If true, then it is a worthy addition to combat against the unarmed Elder types of vampire, with their 15 Aggravated hand damage (e.g. one of the earlier examples, Josef's Tunnels' Nosferatu)
- There is a tactical continuum, usually hidden in class abilities, from most aggressive to most defensive, with damage and damage increase abilities at one end, and damage prevention and healing at the other. Dead enemies do less damage; putting one's efforts into killing them first is preferental. When that strategy comes up short, evasive maneuevers is a good idea, and when that is not enough, there is Fortitude and other damage prevention. This rule might not have survived the roleplaying game's very solid damage prevention, which reduces all types of damage, but Fortitude was hit very hard with the Nerfbat, and only adds an invisible soak (cannot be seen on the 'character sheet', as opposed to the Blood Ritual Ignore the Searing Flame, whose resistance shows up clearly in red on the resistances wheel).