So the text on Yeth Hound reads that each character at the location has to make a wisdom roll or the difficulty of her checks is increased by 1 until the end of the turn.
The way I initially read this is that each character is rolling separately for their own checks to not be increased until the end of the turn. If it said difficulty of "your checks" was increased then I'd assume the rolls all affected the current character but since it says "her checks" it sounds from the wording of the sentence like the rolls all go towards the difficulty of each character that rolls.
After some thought I wondered whether this is intended.
For example - current situation is Ezren and Lem are at the location where the Yeth Hound appeared. It's Ezren's turn, he succeeded at his check, then Lem also has to roll. Other than having to make a spell recharge roll out of turn I'm having trouble coming up with very many situations where Lem would need to make a check out of turn...
I'm probably reading way too much into this card and maybe it's not intended to be much of a penalty but it's almost a pointless increase for an out of turn character. This is why I wondered if maybe it's all supposed to affect the current character.
Well, if Ezren explored again and encountered a "mass encounter" barrier like Zombie Nest, that would mean Lem's failed roll would matter. Or if he found the villain and it was a villain that required multiple checks and Lem wanted/had to take one.
I think it is intended to be as is. The penalty for the character's who weren't the one with the active turn is probably going to be uncommon, but a pain when it does occur.
Ah ok I hadn't considered mass encounters. Thanks for the clarification, I just wasn't sure :)