This is one of those cases where the relevant rule only exists as a response to a rules question. From the arkhamdb page for A Chance Encounter:

• "Does the restriction on 'giving' signature cards to other investigators in the FAQ apply to cards that don't say 'give'? For example, could I use A Chance Encounter to retrieve Duke from "Ashcan" Pete's discard pile and put him into play for me for a turn?" A signature card should not be allowed to be under the control of any investigator other than the investigator named on the card. So, for example, you could not use A Chance Encounter to retrieve Duke from Ashcan Pete’s discard pile if you were playing an investigator other than Ashcan Pete.

If the card is that super-over-powered, then maybe it needs to cost an action to play the card you take to keep it under control.

Or maybe it is too powerful, but also too outrageously random to ever be used, like The Council's Coffer. Which perhaps is a balance all its own.

1 hour ago, CSerpent said:

Oh, good heavens! You can take Diana's Twilight Blade and play more of her cards!

Though I suppose that was already possible with Teamwork.

No, per the FAQ: An investigator cannot control another investigator’s signature cards

I knew this already specifically because of teamwork and just forgot. So that's good. At the very least, we're covering a lot of ground here regarding dusty rules we don't much usually have to think about, haha.

Now, to revisit hidden cards to see if those can be played using YOMO. That could be a good use for the card inside of the Carcosa campaign alone. Are the triggered abilities on the hidden cards considered as if the card is being 'played'? I would guess maybe not because there's no resource cost. Hidden cards are treated as if the card is in your threat area, so you probably can't 'play' it. Correct?

It WOULD however, let you see the hidden card I believe, which in and of itself might be vaguely helpful. Especially in the upcoming Return to Set if you are the kind of group that does blind playthroughs.

The Play and Play Action rules don't explicitly say they only apply to player cards, but they do only refer to assets and events (and skills, to say that you do not play skills).

One funny use of YOMO would be to find a Dark Pact in the hand of your partner...

6 hours ago, Soakman said:

Now, to revisit hidden cards to see if those can be played using YOMO. That could be a good use for the card inside of the Carcosa campaign alone. Are the triggered abilities on the hidden cards considered as if the card is being 'played'? I would guess maybe not because there's no resource cost. Hidden cards are treated as if the card is in your threat area, so you probably can't 'play' it. Correct?

It WOULD however, let you see the hidden card I believe, which in and of itself might be vaguely helpful. Especially in the upcoming Return to Set if you are the kind of group that does blind playthroughs.

That's correct, "YOMO" will certainly let you inspect another player's hand and read the text on their Hidden cards but will not let you clear another player's Hidden card, for two reasons. One, Hidden cards are not Played at all (so "YOMO" cannot interact with them in the first place). Two, the rules text of Hidden is very explicit as to the fact that only the holder of the card can get rid of it:

Quote

While a hidden card is in your hand, treat it as if it were in your threat area. Its Constant abilities are active, and abilities on it can be triggered, but only by you. A hidden card counts toward your hand size, but it cannot be discarded from your hand by any means except those described on the card.

17 minutes ago, vindoq said:

One funny use of YOMO would be to find a Dark Pact in the hand of your partner...

"YOMO!" specifically states that you may play a "non-weakness" card, so no Dark Pact, no The Tower XVI, etc.

You know, it wasn't until I read this thread that I noticed that YOMO didn't have a location restriction - given the title, you'd think the person you're getting payback for past help from would at least have to be within earshot...

And speaking of the title, shouldn't it be "I Owe You One"? It's typically the player of the card saying the quote, and here they're taking something from someone -- they now owe them one.

Nah, it's you telling the other investigator "I'm taking this without your permission because you owe me one. " you say it as you grab the card out of their hand.

4 hours ago, CSerpent said:

And speaking of the title, shouldn't it be "I Owe You One"?

I nearly called it "I Owe You One" a few times. I get that Rogues are selfish jerks, but I was imagining it spoken with fingers figuratively crossed behind the back.

Either way, the card clearly has top-tier flavor text.

I believe YOMO is pronounced "yoink!"