Viridian Transformation Stone

 is a required material for stage 10 weapon breakthroughs.

Acquisition
This can be ordered from the Soul Wardens crafting guild (level 1) in stacks of 5. Each order costs and takes 2 hours.
 * Ingredients:


 * 1 x Viridian poison.png
 * 1 x Gather clear wave pattern green gem.png
 * 1 x Premium Simple Refiner.png

Quest
Finishing the quest A Letter from Hajoon will also reward the player with one of these. If you decide to stick with your Hongmoon weapon for the entire game (in other words, you only ever need to breakthrough one weapon), then the one you get from the quest is enough.