The default rule for the interaction of psionics and magic is simple: Powers interact with spells and spells interact with powers in the same way a spell or normal spell-like ability interacts with another spell or spell-like ability. This is known as psionics-magic transparency.
- Instantaneous Effects: Two or more magical or psionic effects with instantaneous durations work cumulatively when they affect the same object, place, or creature.
- Multiple Effects: Powers or psionic effects usually work as described no matter how many other powers, psionic effects, spells, or magical effects happen to be operating in the same area or on the same recipient. Except in special cases, a power does not affect the way another power or spell operates.
Whenever a power has a specific effect on other powers or spells, the power description explains the effect (and vice versa for spells that affect powers). Several other general rules apply when powers, spells, magical effects, or psionic effects operate in the same place.
- Powers and Spells with Opposite Effects: Powers and spells with opposite effects apply normally, with all bonuses, penalties, or changes accruing in the order that they apply.
Some powers and spells negate or counter each other. This is a special effect that is noted in a power’s or spell’s description.
- Psionics-Magic Transparency: Though not explicitly called out in the spell descriptions or magic item descriptions, spells, spell-like abilities, and magic items that could potentially affect psionics do affect psionics.
When the rule about psionics-magic transparency is in effect, it has the following ramifications.
- Spell resistance is effective against powers, using the same mechanics. Likewise, power resistance is effective against spells, using the same mechanics as spell resistance.
If a creature has one kind of resistance, it is assumed to have the other. (The effects have similar ends despite having been brought about by different means.)
- All spells that dispel magic have equal effect against powers of the same level using the same mechanics, and vice versa.
- The spell detect magic detects powers, their number, and their strength and location within 3 rounds (though a Psicraft check is necessary to identify the discipline of the psionic aura).
- Dead magic areas are also dead psionics areas.
- Stacking Effects: Powers that provide bonuses or penalties on attack rolls, damage rolls, saving throws, and other attributes usually do not stack with themselves.
More generally, two bonuses of the same type don’t stack even if they come from different powers, or one from a power and one from a spell. You use whichever bonus gives you the better result.
- Different Bonus Types: The bonuses or penalties from two different powers, or a power and a spell, stack if the effects are of different types. A bonus that isn’t named (just a +2 bonus rather than a +2 insight bonus) stacks with any bonus.
- Multiple Mental Control Effects: Sometimes psionic or magical effects that establish mental control render one another irrelevant. Mental controls that don’t remove the recipient’s ability to act usually do not interfere with one another, though one may modify another.
If a creature is under the control of two or more creatures, it tends to obey each to the best of its ability, and to the extent of the control each effect allows. If the controlled creature receives conflicting orders simultaneously, the competing controllers must make opposed Charisma checks to determine which one the creature obeys.
- One Effect Makes Another Irrelevant: Sometimes, a power can render another power irrelevant.
- Same Effect More than Once in Different Strengths: In cases when two or more similar or identical effects are operating in the same area or on the same target, but at different strengths, only the best one applies. If one power or spell is dispelled or its duration runs out, the other power or spell remains in effect (assuming its duration has not yet expired).
- Same Effect with Differing Results: The same power or spell can sometimes produce varying effects if applied to the same recipient more than once.
The last effect in a series trumps the others. None of the previous spells or powers are actually removed or dispelled, but their effects become irrelevant while the final spell or power in the series lasts.
