Can all skills and feats be used in conjunction with Magic Jar?

Question

The spell Magic Jar allows you to possess a nearby creature. The spell states:

If you are successful, your life force occupies the host body, and the host's life force is imprisoned in the magic jar. You keep your Intelligence, Wisdom, Charisma, level, class, base attack bonus, base save bonuses, alignment, and mental abilities. The body retains its Strength, Dexterity, Constitution, hit points, natural abilities, and automatic abilities. [...] You can't choose to activate the body's extraordinary or supernatural abilities.

How do you calculate skill modifiers while in the host body? I would definitely recalculate any racial bonuses, but are all skill ranks considered "mental abilities", even for skills such as Fly and Climb?

Even trickier is the matter of feats. There are purely mental feats such as Spell Focus, and then there are feats which seem purely physical such as Fleet and Toughness. Then there are feats like Dodge and Step Up which seem to fall between these two categories.

Is there any good way to determine which feats can and cannot be used while in the host's body?

Answer 1

I suspect there are no written rules about it.

A quick and dirty heuristic could be one of the following:

Skill ranks are training of the body and mind. You retain any skill point spent on mental skills (Int- Wis- and Cha- based ones). You use host's skill points on physical skills: even the Dex- based Thievery is stroed in a sort of body memory so that your fingers actually move by themselves when you are under pressure.

Skill ranks are applied knowledge. You retain all your skill points and ability modifiers on mental skills. You apply half (rounded down) of your skill points and the full host's ability modifiers on physical skills.

On the feat side, we could trace a rough line by stating that pure mental feats are those that don't enhance or modify any of the following stats:

• Hit points
• AC
• Damage reduction
• Damage dealt (if bludgeoning, slashing or piercing)
• Save DC of natural or extraordinary abilities driven through a melee or ranged attack (such as those of the Stunning Fist)
• Fortitude and Reflex saving throws
• Spell Resistance
• Forms of movement
• Physical skills
• Other statistics related to physical abilities (such as the maximum encumbrance)

Furthermore, any host's feat that provides additional maneuvers during melee or ranged attacks, or that provides or enhances other possibilities for changing position or location will be shut down. Possible examples:

• Step Up
• Rapid Shot
• Stunning Fist
• Power Attack

Many of the feats, as you already noticed, are very borderline. However, I'd prefer to be restrictive rather than permissive.