This battle was interesting at least for me, here are the stats for each creature, which is based on medium difficulty.
https://www.dndbeyond.com/monsters/3776464-baldurs-gate-3-phase-spiderhttps://www.dndbeyond.com/monsters/3776156-bg3-phase-spider-matriarchhttps://www.dndbeyond.com/monsters/3776494-bg3-phase-spiderlingIgnore the reaction's on the entries it was just me trying to figure out the code. Matriarch doesn't get two attacks till her rage, at least that's what happened for my two fights with her. There are 16 total spiderlings if she manages to get all three groups spawned (five, five, and six for groups), along with 2 phase spiders.
The interesting part is her rage boosts strength, gives additional attack, and gives -1 to her ac. Both attacks are dex based so the only thing her rage does is the additional attack. Also if you are going by 5e phase spider basic phase spider is a large creature which IS the matriarch, the two phase spiders in the encounter got reduced to medium and spiderlings are tiny.
edit* I did this really late so hoping I transferred all the info i could gather over correctly and it was my first attempt at using that tool, so cut me some slack pls if its not 100%.
