Immunity to effects now functions as superior resistances:
- Effects that deal hit point damage: If you would be immune to that damage, you get energy resistance or damage reduction equal to 2 * (your effective level) ^ 2 against that damage. For example, a 4 hit die skeleton that would be immune to slashing and piercing weapons would receive DR 32/bludgeoning instead.
- Effects that allow saving throws: If you would be immune to an effect that allows a saving throw, you get a bonus to that saving throw equal to 10 + your effective level. Further, if the effect is a save-for-half-damage, then a successful save negates all damage as if the creature had the evasion or stalwart special ability. So a 5th level elf would get a +15 bonus to saves vs. sleep effects. A 10th level character with only two levels of Paladin would still just get +20 bonus to saves vs. fear effects.
- Effects that no not allow saving throws: If you would be immune to an effect that does not normally allow a saving throw, you get a saving throw with a bonus equal to 5 + 1 / 2 your effective level. The default DC of the saving throw is equal to 10 + 1 / 2 HD (or class level of the effect's source) + Cha Mod (of the source or creator of the effect), but the game master might rule that another DC is more appropriate.
- Abilities that overcome immunities: If you would be the source of an effect that normally overcomes the immunities of another target, that target's total resistances (save bonuses, energy resistance, etc.) are halved vs. your effect. For example, a hellfire warlock's hellfire blast overcomes immunity to fire, so a 10th level creature with the fire subtype would only have fire resist 100 vs. the blast.
- Multiple resistances against the same source: If you would get two or more types of resistance bonuses applying toward the same effect, they don't stack, just choose the higher bonus. For example, if you have immunity to both mind-affecting and death effects, you don't get a bonus of 2 x (10 + your effective level) to your saves, you just get 10 + your effective level.
- Immunities granted by items, spells cast by others, etc: If you would get an immunity from an outside source, calculate the benefit based on the source's effective level.
- Possible exceptions: If you would be immune to aging (such as ghosts or those with the Timeless Body class feature), that immunity works normally. If you would be immune to an effect due to lacking the body part or state required for the effect, that immunity works normally (such as a wingless creature being unaffected by the wingbind spell).
Additionally, sentient undead, constructs, and other creatures normally immune to mind-affect effects by nature of their creature type are no longer immune to mind-affecting effects. To be considered sentient, the creature must have an Intelligence, Wisdom, and Charisma score of at least 3.