In Pathfinder Lord of Nothing, to help the Kellids escape from the giants you will have to find a Manticore Tail. However, Manticore tails don't grow on trees, so where to find it?
Where to find the Manticore in Pathfinder: Wrath of The Righteous
To be able to start the ritual you will have to find weapons for the Kellids, free the tanners, and acquire a Manticore's tail. While the first two quests are more intuitive, it is possible to miss the spot where the Manticore is hiding.
The map below shows the location of the cave. You can investigate the animal carcass on the ground, and your party will say they should lure out the Manticore with some meat.
Where to find meat in the Verdant Caves
If you head to the far top right corner of the map, you will find the tanners at work, being watched by two giants. I got rid of the giants by putting a Potion of Reduce Person in their food, and attacking them while they were under the effect.
Regardless of the approach you take, with them gone you can loot a cart that contains three pieces of meat. Place the meat where you found the animal carcass, and the Manticore will come out. Sadly, there is no way of cutting a Manticore's tail without killing said Manticore, so be prepared to fight.
For more on Pathfinder: Wrath of the Righteous, check out Should you kill the Translator in Pathfinder Lord of Nothing? here on Pro Game Guides