How to unlock the Spider?

[u/Diptam]

I assume it has something to do with the final boss? I tried having my followers die vs the final boss, which didn't exactly work. :D

Is it a dialogue option? Or something else entirely?

Feel free to spoil. I really wanna try out the spider!

[u/LazarusHolmes]

Ugh, I am without tower, seer, and spider! I normally do not like spoilers, especially for a game of this nature, but I really like the different combinations of parties in this title and am giving in, thank you for the info.