Creepy crawlies and a near TPK

Late in the afternoon on Planting 16, SWAG searched the room of High Priestess Lanthurrae, finding several magic items and the following note:
The note was signed with only the following cryptic symbol,
resembling the symbol on the note to Noak the black dragon:

SWAG thoroughly searched the room and heard a humming sound coming from the south. Mosaic footprints on the floor entered the room from the south and exited to the west. SWAG barred the southern door and proceeded out to the west. In a room half-blocked by a cave-in, SWAG fought three spiders the size of wolves. After fending them off, three more web-spinning spiders attacked from the south. After a lengthy battle, all the spiders were killed and SWAG searched these rooms.

SWAG then proceeded south, following the mosiac footprints to double doors. SWAG opened these doors to reveal a room covered in webs, with a huge fiendish spider the size of a small hut patrolling the room, near an altar with a glowing green statue. Quintavian asked whether it might be better to just shut the door. Carrack entered the room and quickly became entangled in the floor webbing. Red and Petra stormed into the room, while the spider shot a web at Petra entangling her too. Quintavian and Erlwyn attempted to free Carrack, discovering that the webbing was hard and difficult to escape, while Red charged the spider and also became entangled.

The massive spider then began its direct attacks, causing large amounts of damage to the entangled Red and poisoning him, sapping his strength. Carrack fired multiple sound bursts from his newly found wand, occasionally penetrating the spider's spell resistance. The spider attacked Petra, biting her into unconsciousness. With most of SWAG entangled, Red badly wounded, Petra dying, and a mostly unharmed spider, Quintavian questioned why everyone went in the room while she waited safely outside. She and Erlwyn kept trying to free Carrack, while a lucky sound burst finally penetrated the spider's resistance and stunned it for a turn.

Red hacked himself free of the webbing and grabbed the dying Petra on his back. The nearly defeated group tried desperately to escape the spider's lair. Red hurled Petra to the ground near the exit and helped free Carrack. The spider then bit Red again, knocking him down to -8 hp. Who would rescue Red now? Carrack cast cure light wounds in a desperate attempt to save Red, and rolled an 8, healing 9 hp for Red. Carrack raced past the spider to freedom, discovering that his wand of sound burst was now exhausted of charges. Red stumbled up and fled the room, lucky to be alive. The group dragged Petra away. All ran away, to heal and fight on another day...