Search Warslik's Woods for 8 Redscale Pitcher Leaves.
Note: This is a small dark bluish-black plant that is not trackable. They are abundant in the Warslik's Woods area between Nye'Caelona, Slaver's Point, and Warslik's Woods poi's on the map. I didn't find any at all near Chalp or Twark areas of Warslik's Woods.
Return to Savix'Host and make him take the medicine.
Take him to Crusader's Cave.
Note: You can fly directly to Crusader Tarrac at the inner gate of the cave to escort him there, but walk up the stairs to him to update the quest correctly