Affliction Resistance, also known as Wound Fend, prevents Afflictions from occurring. This is portrayed in various forms; as unusual resilience in the respective organs/bones, and as a sort of fluidness that makes structural damage difficult.
The former kind is given by Earth magic, though mainly indirectly; for example, those with 
4 or higher get Affliction Resistance 1, while an Earth Bless can grant Affliction Resistance 3. The latter kind is given by Water magic through the Liquid Body chain of spells; these grant Affliction Resistance 1. These stack but are otherwise all the same effect.
Affliction Resistance provides a chance to disregard the actual odds of a hit causing an Affliction, making those odds 1-in-200 instead. This could, in theory, make Afflictions more likely to happen, but those cases are very rare; a fellow with 300 max HP taking 1 point of damage, for example. The odds of Affliction Resistance kicking in are equal to the point value, divided by the point value plus 1:
| Affliction Resistance | Chance to Kick In |
|---|---|
| 0 | 0/1 (0%) |
| 1 | 1/2 (50%) |
| 2 | 2/3 (66%) |
| 3 | 3/4 (75%) |
| 4 | 4/5 (80%) |
| n | n ÷ (n + 1) |
| 99 | 99/100 (99%) |
Affliction Resistance overrides Curses and Regeneration, if it kicks in. You can look at it from the other direction, though, with Regeneration quickly trying to fix the stuff that got through Affliction Resistance.