Available at the Alchemist for 5,000 
Cor Draconis (Rough).
Increases eligible positive monster, Metin, boss and dungeon bonuses on stones in your active Alchemy deck by 50%. Each contribution rounds down. Permanent stones are included.
Each item provides 2 hours of combat use. The timer pauses outside combat and when Alchemy is inactive.
Set bonuses, Guild Alchemy and other attributes stay unchanged.