The Taken Wenja
Head over to the Tensay map marker to enter the mission area.
Head over to the battle site to start the mission.
As per all tracking missions, turn on your hunter vision to easily see the tracks. There are a bunch of arrows and spears littered through the track so you may stock up in case you were not on full stock.
You will find burnt corpses of fallen wenja indicating that they have lost the battle.
Head into the submerged cave. You can find some bloody handprints on the walls. Hunter vision shows up clearly.
You will eventually come out of the cave and see some izila that have captured an Udam and a Wenja. Things quickly turn bad for the Udam. Your wenja brother will be sacrificed though.
You will now be tasked in burning their camp. This goes just like all the destroy missions go. Light your weapons ablaze and set things on fire.
TIP: Release the captured wenja to help you in this mission because setting structures on fire will summon more enemies. Having the wenja around to help makes things quicker.
After burning the camp up, leave the area. However, you are ambushed by the enemy and are taken hostage.
You meet the Izila's leader, Batari. She offers to spare you if you serve only her. You refuse so she throws you into the burning pit.
After falling into the burning pit, you may be injured and even burning. Heal immediately if need be. Face the east and look for a body of water. It has an underwater tunnel that leads out.
You may choose to go back into the camp and kill the izila in there but this offers no bonus whatsoever. You can do that or just simply exit the area.
After the short cutscene with Tensay, he will say that Batari uses the wenja as slaves in the marshlands. He also shows you a izilan camp you can capture.