You get this near the end of episode 2. You need 5 particular items. Matches, feather, plant, fish skeleton, Tigren's locket. Return to Tigren's Lair. Interact with the ritual altar. There's 5 elements. Place the right item with the correct element.
Fire - matches
Air - feather
Earth - plant
Water - fish skeleton
Love - Tigren's Locket
After placing the items, a doorway will open and the achievement will pop.