Fortitude is a Discipline that grants Kindred unearthly toughness, even to the point of resisting fire and sunlight.

Personal Armor (Rank 1)
Take less damage

Resilient Minds (Rank 2)
Mind altering powers succeed less on you

Armor of Kings (Rank 3)
Weapons that hit you may break, gain a significant amount of armor.

King of the Mountain (Rank 4)
Focus purely on defense blocking all attacks, at the expense of all else.

Repair the Undead Flesh (Rank 5)
Heal yourself greatly