Hopefully this is a bug. Not a fan forced use of tadpole. I couldn't even use the sigil/stone/whatever to open it.
You're not forced. Like I did, you have a choice to tell SH, "Sorry. I can't find a way to open it.". Then you'll see her again by the crypt. It's not that big a deal if you don't give in to the dark side. That's part of why I think it's a good temptation. It's not "SH will literally die if you don't use the tadpole, Luke."
Sorry haven't played it yet. Is this encounter bugged or not? Someone said the tadpole option just said Wisdom not Illithid Wisdom. There is no problem to me with having tempting situations come up for using the tadpole. There is a problem not telling me I'm using it.
I have to wonder where the two paths will diverge, if they even do diverge when it comes to the illithid powers. Will there be a point where if you've used the powers a certain amount, you no longer have a choice in a story point? Or will people that never used them and those that used them constantly end up with the same choices in the end? It would be disappointing to have something so integral to the game end up meaning not much at all.
That said, if they're going to make using illithid devices use illithid powers, then they should be consistent. Elevator? powers. Healing station? powers. using the console in the bridge? powers. Otherwise, this one decision ends up very much seeming like a "you want cute girl? you use bad powers" moment.
This divergence is imo going to be important, and I'm afraid Larian is pushing for the assumption most people will interact with it some. I'm not sure a "good" player who never once uses the tadpole is going to end up all that different, if not overall indeed worse off... like the tadpole using player ends up able to complete the game, somehow cures the tadpole but still gets to keep the powers.
Back at patch 3 I did some testing with Omeluum...
https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=751014&page=1 I haven't played since the druid patch and haven't been to Grimforge, so there have been changes and additions since my testing. Omeluum's initial assessment of the tadpole was the same regardless of level of use.
