This article contains lore taken from Warcraft III: Reign of Chaos, Warcraft III: The Frozen Throne, the manuals, and/or official bonus maps.
When the Burning Legion went to Kalimdor after destroying Lordaeron, Mannoroth and Tichondrius went to glade in Ashenvale to consider using the Orcs to defeat Cenarius. Mannoroth proceeded to spill his burning blood into the Fountain of Life, corrupting it, causing anyone who drinks of it to be infused with chaos. When Cenarius attacked the Orcs, Grom Hellscream took a detachment to explore the forest. They found the Chaos Well and drank it, reinstating the blood pact between them and Mannoroth. The Orcs proceeded to use their new found power to kill Cenarius and the Night Elves.
The Chaos Well, a corrupted Fountain of Life.