I want to activate a magic item using Command Words. I don't need to disguise the effect or that I used a command word at all. However, I want to disguise what the command word is, such as by saying a bunch of words and hiding which one of them was the command word.
What type of check would that be? Bluff, linguistics, spellcraft, UMD, or something else?
A bluff check is used to trick verbally someone, so i would say you are simply using the command word inside a random phrase that you came up with and ask you to roll a Bluff vs Sense Motive so people can notice you are trying to pull something off (but they wouldnt know what).
If we actually check the Bluff skill, we can see that there is validity in that ruling, as you are trying to pass a secret message to the item:
Convey Secret Message
You can use Bluff to pass hidden messages to another character without others understanding your true meaning. The DC of this check is 15 for simple messages and 20 for complex messages. If you are successful, the target automatically understands you, assuming you are speaking in a language that it understands. If your check fails by 5 or more, you deliver the wrong message. Other creatures that hear the message can decipher the message by succeeding at an opposed Sense Motive check against your Bluff result.
So, lets say you are trying to activate a +1 Flaming Sword that has the Flame On! command word, your character would use those words inside a phrase so others wouldnt notice what he actually did, like:
"It's so hot in here that seems like someone threw a flame on me."
Take a free action to speak. Take a standard action to activate the command word activated magic item. Take a free action to speak again.
Your Turn
- Free action to speak: "I smell the flowers, pet the unicorns' horns, and taste the...
- Standard action to use the command word activated magic item: "...effervescent...
- Free action to speak: "...waters of the countryside's clearest rivers."
I mean, really, if you don't care about concealing the effect or that you used the item, caring only that you bury the command word among nonsense, swearing, and embarrassing personal revelations, that's fine. Shoving the command word into, for example, the middle of your lecture on beholder interior decorating only makes the foe who heard you deliver the lecture and who subsequently takes and tries to activate the item look foolish until the foe can tease from your lecture the correct individual command word. In the interim, such a ruse makes you look foolish and annoys your friends. (Nonetheless, despite all this, I've had players for whom such a petty revenge would taste very sweet, so it's cool.)
The concealed command word ruse likely won't last long after you've lost possession of the magic item. Using Items on Command Words says that
Sometimes the command word to activate an item is written right on the item. Occasionally, it might be hidden within a pattern or design engraved, carved, or built into the item, or the item might bear a clue to the command word.
So check the item before you start this plan, I guess? Then the section continues, saying
The Knowledge (arcana) and Knowledge (history) skills might be useful in helping to identify command words or deciphering clues regarding them. A successful check against DC 30 is needed to come up with the word itself.
So aside from using spells like detect magic, identify, analyze dweomer, commune, legend lore, vision, contact other plane, arcane sight or any of the other many ways to glean a command word, the GM may rule any dude getting a high enough result on the appropriate skill check determines the item's command word. In fact, the GM may rule that that dude needn't've even first heard the embarrassing sentence you shouted when you used the item, making all your efforts for naught, which is sad.
Bluff could stop someone realizing a command word was used, as previously stated, however no Sense Motive (shy of maybe the epic mind reading rules) will ever intuit the actual command word from the spoken sentence.
For someone to figure out what was the actual command word, I'd call for at Intelligence check, DC based on what was said (how many words or phrases said could logically be the command word based on relevance, assuming it is relevant to the effect), with a bonus if the person attempting to guess it has witnessed it multiple times (bigger and stacking if they've heard multiple different valid phrases).
For me this wouldn't be a skill check (why would you need to roll to see if someone noticed you talking as a part of an attack - and why would it matter if they did?) but would be a roleplaying type of a thing Are you familiar with anime "called attacks?" http://tvtropes.org/pmwiki/pmwiki.php/Main/CallingYourAttacks talks about it. Basically the idea behind it is that the command triggers the attack. (though a character can lampshade doing that type of a thing)
