Fighting a spider matriarch should be a tough fight. All fights in DND games are optional to a greater or lesser degree. If you save often you have several things you can try:
Come back when you have gained a level.
Come back when you have better gear.
Come back when you have re-jigged your spellbook to deal with this type of enemy.
Drop the game difficulty for this particular fight.
Look on YT for vids showing how to do this fight.
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When was the last time you saw a spider fall? Breaking the web bridges is pure Larian cheese.
My main problems with the fight came from the camera. In my first attempt of this play I was getting hammered by poison being spit and the phase spiders were phasing out to who knows where because the combination of narrow spaces and 'verticality' completely screwed the camera. I ended up reloading before I was actually party-wiped and came back a day or two later, made sure the height difference between the party and the spiders wasn't as great and did the fight in a few minutes with minimum fuss.
There's been a couple of fights where verticality + camera has caused more problems than the enemy.
