Phantasmal Force

Q: Do Phantasmal Forces with say 20% of Reality do that 20% of damage if the victim saves and 100% damage if the victim fails the save, or b) no damage if the victim saves, and the 20% of damage if the victim fails the save?

A victim who saves takes 20% damage from a 20% real phantasmal force. A victim who fails believes they have taken 100% damage, but only 20% of it is real. The extra 80% disappears as soon as the duration of the effect expires, and the injured character can immediately act based on their condition appropriate to their real hit point total.

A victim who believes they have been knocked unconscious or killed falls prone and loses their active bonus to defense, but is not helpless.

Q: Also on Phantasmal Forces, does the % of reality translate into anything other than damage? (Can a bridge with % reality hold up a person, etc.?)

The description of the spell method clearly implies that a phantasmal force wall would block movement ... but that could be because the creature believes itself to be blocked. The question with a bridge isn’t about fooling a creature, it's "can you fool gravity?" or "how real is 20% real?"

My suggestion on this one would be: multiply the number of squares of the phantasmal force by the % reality and round down. That’s the number of squares that can be safely occupied at any one time.

So, a huge (9 square) bridge that was 20% real could support 1 square’s worth of burden (9 x 20% = 1.8, rounding down to 1). A single medium or small sized character could cross that bridge. If two such characters were on it at once, it would give way.

I expect a lot of folks will house rule differently on this one, but that’s what I would do.

Veil of Trickey

Q: Veil of Trickery can, with Blurred Image, offer a Concealment Miss Chance of up to 95%. Since being totally blind is only a 50% miss chance couldn't a character simply decide to close his eyes and blind fight thus reducing his miss chance to 50%?

Sure, as long as the character wasn't mindless. But keep in mind that there are major penalties for being blinded (which someone with his eyes closed is considered to be) and that smart opponents will ready actions to thwart you ("I ready for him to close his eyes, then 5ft step so he's attacking the wrong square and power attack full while he has no active defense. Did I mention I have +5d6 sneak attack?").

How do I ...

Q: create an illusion of fog - this seems like a sensory deprivation with a large area, correct?

This is a phantasmal force effect for the visual aspects of the fog, and a sensory deception effect for the cold, clammy 'feel' of the fog and the way it deadens sound. I'd allow a character to try and create a visual-only fog, but give creatures witnessing it a bonus to notice it was fake due to the lack of other sensory effects.

Q: create an illusion that one opponent (or more) sees humans as something else, for example, fellow orcs - I have no idea how to adjudicate this other than to say it is a colossal sized phantasmal forces

Even a colossal area is only 25 squares - that means if the target creature is at the centre of the effect, anyone more than 2 squares away would look normal. So I don't think phantasmal force will work.

I'd use the mechanics of veil of trickery (alter features) for this, but instead of it changing the features of the target creature, it changes their perceptions (ie everyone they see gets a Disguise bonus to look like an Orc). I'd probably allow it to be cast at range by spending extra mana (0 points = touch, 1 point = 25 ft + 5 ft/2 mastery, 3 points = 100 ft + 10 ft/mastery, 6 points = 400 ft + 40 ft/mastery). In this case, range means 'caster's distance from the target at time of casting', not 'how far from the target people still look like orcs to them'. The target gets a Will save against the effect, of course (just like normal veil fo trickery, but no longer harmless)

Using the veil of trickery approach makes this very expensive and time-consuming to do to lots of people, but I think that's appropriate.