"It is in my nature"

The party (minus Graal, plus the head of the lion guard Kestral, heads up river to investigate the source of the poisoning and illness of the people of Ar-Ensul. They are attacked by Stirges one night, but the bloodsuckers are quickly rended disabled by the magic dust thrown at them by Kestral (this also injured Linneaus and Ferrethryn). Later they stumbled upon the source of the bad water. Hidden by illusions there were two carcasses of huge bison rotting and bleeding poison were tied up in the river. After investigating briefly the party was attacked by a group of giant scorpions. The party succeeded in killing those fairly quickly, but not before they did some damage to the party.
The group eventually crossed the river (not without some trouble) and pursued the creatures. They found the skeleton of a giant, and were ambushed again an illusionary hiding place, and made a pitched battle. The party, Kestral in particular were seriously injured, but the gargantuan scorpion and its smaller riders were taken out. A cursary investigation of the cave revealed yet another illusion. This one hid one more scorpion, and a strange scorpion-folk who appeared to be a spell caster.
A short battle killed the scorpion, and the party parlayed with the leader. He admitted to being hired to poison the river by the giant and a sibbecai (by the name of Garman). The Party allowed him to leave, but cast magics on items and the bones to learn more about the scene.
The party obtained a magical talisman which grants a bonus to fortitude saves and ???

Does anyone have the names and other data from this adventure?
Afterwards they returned to

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