Gwydion fab Dôn is a magician, hero and trickster of Welsh mythology, appearing most prominently in the Fourth Branch of the Mabinogi, which focuses largely on his relationship with his young nephew, Lleu Llaw Gyffes. He also appears prominently in the Welsh Triads, the Book of Taliesin and the Stanzas of the Graves.
The name Gwydion (which should more properly be spelled Gwyddien in Modern Welsh, as can be adduced from its Old Welsh form Guidgen; cognate with Old Irish Fidgen) may be interpreted as "Born of Trees".
Gilfaethwy, nephew to the Venedotian king, Math fab Mathonwy, becomes obsessed with his uncle's virgin foot-holder, Goewin. His brother Gwydion conspires to start a war between the north and the south, so as give the brothers the opportunity to rape Goewin while Math is distracted. To this end, Gwydion employs his magic powers to steal a number of otherworldly pigs from the Demetian king, Pryderi, who retaliates by marching on Gwynedd. Meanwhile, Gwydion and Gilfaethwy attack and rape Goewin.
Forged and bred to rule the heavens
Son of the glorious immortal Don
Possessed his Castle amidst the stars
The greatest galaxy known as the Milky Way
Bright pupil of the wise Math
Learned magic lore with outstanding skill
Through years of learning hardships
Finally He's proclaimed as the Druid of Gods
Lord of Illusion and Fantasy
Fought with Govannan against ignorance
Gwydio's obscure side
Helps his brother Gilfaethwy
Releasing his lust for Goewin
Maiden of King Math
Deceive is the way to her flesh
So forge a war to absorb the king
Then invade the unprotected rooms
And incest in royal sheets
Disguise thyself in ten bards
Trade the swine with your cards
Make all illusions become I'll