Well we know that while hardly any she still has some divine powers... corrupted as they are.
I honestly always thought she bullshited in that scene... but let's assume it's true... she made an oracle for finding "a tool" that could provide her with power or atleast could be used to further her plans for vengence... and she learned that MC would visit her hut in a few days or weeks.
I mean if we spin this thought further there is even more... her connection to Gromthul and Syfa could mean that the attack on MC and Marcus wasn't even coincidental... let's assume Isha asked/demanded this attack from Syfa and they gave that old Orc hag wich is the chieftains wife a vission on which Gurthak had to ambush MC and Marcus at the bridge.
The gods had always been known to mingle with human fate in cruel ways... devasted MC would seek shelter maybe they even manipulated Rick to remember this shack while giving missleading directions.
It COULD have all been a coincedent or fate encounter... but the more I think about it the more it seems fitting that it was orcastrated by someone with a MUCH bigger plan and higher level of situational understanding.... like a goddess
A plan that would have completely fallen apart if Rick had been too drunk or completely forgot about that house he only knows through hearsay. Or if MC had found the actual cabin Rick was talking about (which isn't even Isha's house, I'll remind you). Or if Rick had given better directions. Or if MC had decided not to refuse Mira's offer to help (even Emily would've accepted for the first night while he's still mourning). Or if MC had asked around the village and found that Penny was willing to help him. Or if MC had failed to survive the orc encounter. Etc, etc.
Yeah, unlikely. That was just bullshit she spewed to make an impression. If she had been able to craft a plan that masterfully, she wouldn't have taken in someone like Sabrina in the first place. Nah, it's much more likely that it's a tale she'd have told any who had been caught in her "trap". Stories with foretelling etc usually fail spectacularly at staying coherent. Instead, if Isha simply couldn't be bothered to clean all that time, noticed an intruder approaching, prepared the trap, hid, and later cleaned up everything because having sex in the middle of cobwebs sucks (+ to make a stronger impression), that'd be making way more sense.
Also fits more with what we know of Isha. She's pretty self-absorbed and absorbed in what she does, yet at the same time she's crafty. Simply continuing her research then quickly coming up with a plan to ensnare MC who she senses approaching fits the concept of a fallen goddess with little power left far more than foretelling his arrival, preparing absolutely everything, influencing everyone, relying on a lot of flimsy or random elements (the failure of any of which spelling doom for her whole plan) so that MC would eventually find his way in her home. That's the sort of convoluted mess that makes people roll their eyes saying "Sure, whatever. Let's roll with that I guess", testing the limits of their suspension of disbelief.