Constitution

From HGWiki

Constitution represents the health and stamina of your character. High Constitution increases the number of Hit Points a character has (affecting how much damage they can take), and this makes it important for everyone, but especially so for fighters. It is the casting stat for Accursed Pariah characters. If Constitution ever increases, hit points increase retroactively as well. Spellcasters also need strong Constitution to keep their spells from being interrupted during combat. Your constitution modifier is added to all fortitude saving throws.

Further Information

• Any living creature has at least 1 point of Constitution.
• Having a score of 0 means that the character is dead.
• A creature with no Constitution score has no corporeal body (a spectre, for example). It is immune to any effect that requires a Fortitude save unless the effect works on objects. For example, a zombie is unaffected by any type of poison but is susceptible to any kind of disintegration. The creature is also immune to ability damage, ability drain, and always fails Constitution checks.