If I attack someone using Cersie and they use Pentoshi Manor on me, I assume I only lose any current keywords ... so if I win the (intrigue) challenge I can then give Cersie stealth or deadly?

Challenges: Kneel Pentoshi Manor to choose an opponent's attacking character. The controller of that character chooses to either have that character claim 1 power and remove it from the challenge, or that character gets -2 STR and loses all keywords until the end of the phase.

... Cersei Lannister gains your choice of stealth or deadly until the end of the phase.

I have doubts on that interpretation. The way Pentoshi reads, "loses all keywords until the end of the phase" reads as a lasting effect. That would mean, in my interpretation, coupled with the new definition of "lose all X" = "lose 1 of every," that would mean Cersei would lose 1 instance of every keyword in the game at the resolution of Pentoshi's effect (whether she currently had that keyword or not). So, even if you add Stealth to her later, she would not have stealth until you added stealth a second time.

I know what your saying, and that is the crux of the issue

But if Cersie does not have stealth at the time Pentoshi is triggered, are we saying that that means she is effectively sitting on -1 copy of Stealth and therefore needs 2 copies to get up to 1?

That doesn't sound correct - in most things AGOT you do not count below zero

Lose All / Lost All Instances:

I checked the previous response by ktom re "lose all" - I think I may have misunderstood his comment

Unless a card specifically says that you lose "all instances" of an icon/keyword, you only lose one. So 99.999% of the time, you only lose one

So LOSE ALL - means lose one of each / LOSE ALL INSTANCES - means lose all instances of each?

I was thinking that the ALL word was the relevent word as opposed to INSTANCES

I shouldn't have said "instance" because that does confuse the issue due to the specific FAQ verbiage. While it isn't incorrectly used, it can confuse the issue. I should have used "copy."

But, yes, due to the way Pentoshi Manor is worded "loses all keywords until the end of the phase" it creates a lasting effect where the character gets -1 of every keyword in the game, so Cersei is effectively sitting at -1 stealth at the resolution of Pentoshi's effect (and -1 infamy, and -1 immune to events, and -1 [every other keyword in the game]).

The ALL word is still the relevant word. The word (or words) you're looking for ("printed" or "all keywords it currently has") isn't there. There isn't anything that says a character can't lose what they don't yet have. There are effects that strip 1 of every icon from a character (even if they don't have the icon). They are technically at -1 of that icon and would require TWO adds to gain the icon.

That doesn't sound correct - in most things AGOT you do not count below zero

Actually, you do. For keywords, traits, strength - any number less than 0 is functionally 0, but every time you add (or remove) you recalculate and get a new total.

If I have a 0str character, you give him a lasting -2 str, then later I give him a +5 str boost, his total strength with be 0-2+5=3. It doesn't matter that his effective strength was 0 while he was under the -2 effect.

You are getting good advice from doulos2k and -Istaril.

The word "instances" is, indeed, the relevant word in determining the difference between "lose all keywords" and "lose all instances of that/those keywords." The comment about "99.999%" is more about how uncommon (as in, "never") it is to see the term "all instances" in card text.

You should also note that the question answered by your quoted comment was effectively "if a character has stealth printed, gains stealth from a card effect, then loses 'all keywords,' will it be able to bypass something or not?" The answer was "1 (printed) + 1 (gained) - 1 (lost) = 1; so yes, the card can bypass something."

That answer leads you to what -Istaril is telling you: the order that modifiers are applied almost never matters. You always "start from scratch" when determining the result. So yes, things count less than zero all the time in this game when determining a card's status or characteristics. It's just that most of those characteristics interact in a "have or have not" kind of way. Having stealth twice, for example, doesn't let you bypass two characters because that's not how stealth works. Similarly, having -1 stealth doesn't make a character "more obvious."

Thanks - that all makes sense, especially when taking into account that values are always recalculated