It probably has no use whatsoever (except maybe for draw...), but I just wondered - can I use Pentos to save a character from being killed by my own Festering Wound by discarding it?
I think yes, because it removes the character from terminal state - the card that caused the effect "lower STR, die if 0" is no longer in play. However, my timing might be off. Would that work?
Yes, you could indeed do that. Since you are getting rid of the attachment at the same time.
Actually, by discarding your own Festering Wound to save your 3-STR character from being killed BY that Festering Wound, you make the attachment moribund until the end of the action window. That does NOT "turn off" the attachment's passive effect on the attached character. The attachment is STILL killing the (non-moribund) character, which is therefore not removed from the terminal state. Hence, even trying to save by this method is illegal.
So no, you cannot use Pentos to save in a situation like this because the save does not actually get rid of the attachment "at the same time." The attachment effect lingers because of moribund. (It's different from making the attached character moribund since you cannot kill a moribund character a "second" time.)