Devlin is a warlock that led a warlock faction. He was able to steal the Ring of Inspiration to have his fellow warlocks aid him in ruling the Underworld. The Charmed Ones were able to stop him, recovering the appropriated Ring Of Inspiration, and finishing him with the Warlock Vanquishing Spell.

Spell to Vanquish Devlin:
Evil is a faithful foe
But good does battle best
We witches will with these words
Waste this warlock's evil zest