Patryn of Elvenshae said:
For the record, my first guess would have been "Invisible spellcaster," not "magical trap."
I generally expect traps - magical or otherwise - to have some pretty specific logic to their placement. The middle of a random corridor doesn't cut it, in my mind. A locked and barred door? Sure. A treasure chest? Absolutely.
I think the fact that you make assumptions as a player doesn't mean the GM did a poor job. Your logic may have nothing to do with the logic of the trap-setter - and if I'm designing traps, I definitely set them in places where adventurers wouldn't automatically expect to find them (or not find them).
I'm sorry, but I think
Patryn of Elvenshae and
Brother Shatterstone are offering (mostly) poor advice here. I don't see any problem with how the GM adjudicated the traps other than perhaps offering a small chance to observe the trigger, as was mentioned.
The Thayan Menace described the spell effect, and the casters in the party knew it was a spell - if the player of the rogue made incorrect assumptions about it and the other players failed to offer assistance, that's not the GM's fault.
I don't give my players broad clues like, "So-and-so is known for magical traps," or, "You suspect a trap because you are an
n-level rogue." These are things I expect them to discover in-game, like talking to a loremaster about So-and-so's penchant for traps before entering the fortress or using the skills that an
n-level rogue brings to the adventure - at the very least the player should know his own character's skills and try to use them. As far as the action and skill checks go, if I think a character should have a chance to know something that the
player missed, I'll ask for a skill roll and then offer them a clue, but I don't just hand the information out when a player makes a bad choice or misses a roll.
Patryn of Elvenshae said:
And a better description might have been, "As soon as Bob crosses [point X], blah blah blah."
If the player says, "My character moves to
X," and I describe some effect, then that's all the warning s/he gets unless s/he gives me something more to work with, like, "Was it when I reached the statue, or before that?"