A few points here:
The argument is that we were using out of character information about a failed Will save. That argument implies that if a Will save were never rolled then we would never had suspected the body of being an illusion.
Lets assume the DM knew everyone’s will save, and rolled them in secret to find that we all failed. When we get the idea that the corpse is a fake the DM could just say, “Looks perfectly real” without even calling for a saving throw. At that point we still would have thought the corpse was a fake and done a thorough investigation of the coffin*2. There would have been no out of character knowledge of a Will save, therefore, all metagaming arguments would fall flat.*3
Lets say your DM is running a particular module. You happen to have read part of this particular module before and know of a location of a secret door. You don’t want to use metagaming, but by a certain point your character has overwhelming proof that a secret door exists. So you search the area for a door. Your DM, who knows you read the module before, claims you are metagaming. You try to explain that you did know about the secret door before hand, but the evidence you character has is more then enough to convince him a door is there.*1 You DM doesn’t care, your mind had been compromised out of character knowledge. Now matter how much evidence your character has, he can “never” search for that door. *A
That’s the argument being made against the party. The claim is that the knowledge of a Will save being rolled “compromised” us, and from now on, all actions we take are suspect.*4
*A: If this is what you have done previously then searching should be fine. But again I'll ask: At what point do you then accept that there is NOT a secret door there?
*1 To fully compare the two, don't you need to add: I've failed my search, but there is absolutely no way/solution/explanation OTHER than a secret door to be there, therefore there is a secret door here somewhere.
Or is the fact that there is a missing kama considered overwhelming evidence that the body is an illusion? I know it is evidence that something might be screwy around here but illusion is only one possible answer.
*2: Then why wait until after the failed save to detect magic? From your posts it is only AFTER the missing kama is noticed and then AFTER the will save failed have you done anything to prove that the body is an illusion. All fears that this was not the body, that this
is an illusion, certainly not some other trick come after the failed save.
Given that it seems you were expecting a trick, that the body was thought to be a fake (from later posts), it seems very strange that every attempt to check for such tricks happened after the failed save, and the only attempts to find what was going on were aimed at the trick being an illusion (from your first post).
That is where the calls of metagaming are coming in.
To me, the only way this might not be metagaming is if illusion is the only trick the the DM EVER tries. The PCs are then fine to say: the only trick we encounter is illusions, so if this is an illusion (on the kama, on the body) detect magic will reveal it.
*3 Possibly, but I don't feel that is a reasonable argument because:
This is the central issue: the timing of actions, cause and effect. (Don't think I'm making a strong case on this point
).
*4 Not all actions, just actions specifically to determine that the body is in fact an illusion. Several posters have said: Search for the kama with detect magic:
. Search for secret compartments for the kama:
. Something is definitely not right, how do we figure out what is going on?
. This has got to be an illusion
.
Something that hasn't been bought up yet. How do the PC's it is a magical kama? My assumption would be because it had some magical properties that make it obvious such as shedding light, flaming or similar properties?