Is there anything I need to know about The Nadir?

So, when or if I get a eyeless skull and enough supplies, I can finally go and try and find The Nadir. My question is what do I need to know about it first? I have heard both good and ill.

Every action in the Nadir saturates you with more and more Irrigo. The more Irrigo you’re hit with, the more stats you lose when you leave. If you get as high as 10, you’ll panic and have to leave immediately, and the stat penalty will be double. Oh, and some actions give you more Irrigo than others, so you’ll want to be selective.

(Oh, and also: the first time you visit, you’ll be drawing cards related to your companions. I think you have to play all of those before you leave, or their story won’t trigger when you get out and you won’t get that part of your reward. I’m not 100% on that because I haven’t quite been able to figure out which options are counted as being friendly toward them and which as hostile - I find it a bit confusing, honestly!)
edited by Sir Frederick Tanah-Chook on 11/30/2014

[quote=Sir Frederick Tanah-Chook]If you get as high as 10, you’ll panic and have to leave immediately, and the stat penalty will be double.[/quote]More specifically, you’ll lose 50 CP in every stat while ‘struggling for the exit’, and then you lose 5 CP for every level of irrigo when you actually leave, which comes to a total of 100 CP at irrigo 10. But since you can play a card at irrigo 9, and get +2 irrigo from that card, you can easily end up at irrigo 11, which is a total loss of 105 CP to every stat and not quite double, which would’ve been 110 CP.

And already at irrigo 6 you start losing 5 CP instead of 1 CP per level of irrigo, so unless you’re stat-capped I would suggest making sure to not go over 5 irrigo, unless the last card you draw is one of the two cards that give you a 62.50 Echo item. Which cards are those? Well, the safest way to play the Game of Nadir is to read the wiki. One of those two cards works best if you have plenty of Confident Smiles to burn, particularly if you have low Persuasive. The other only works if you have at least three second chances of the same type to spend. So be sure to have some when you enter the cave.

I only needed to play one of the Missionary/Firebrand cards in order to complete that storyline; there may be more than one that one can play, but I never encountered more than one in my first visit.