Gwydion is a Celtic God who is part of a triplicity of deities, each one the sons of the Goddess Don. He is the nephew of Math, lord of the Welse kingdom of Gwynedd and his father was Beli. Some consider him to be a trickster, but he is very good at art, magick, and battle.
This deity had a brother named Amaethon who stole a hound, deer and bird from Annwn, the lord of the otherworld. This caused the Battle of the Trees (Cad Guddeu). Gwydion and his brothers fought Annwn in this battle and Gwydion enchanted “elementary trees and sedges”to become warriors and to fight against Annwn’s forces.
The Alder lead the attack, and the Aspen fell in battle. Heaven and earth trembled before the Oak, a “valiant door keeper against the enemy”. The Bluebells combined to cause a dismay, but the hero was the Holly. No enemy alongside Annwn could be vanquished unless they could guess his name. Gwyden guessed his name and said:
“Sure-hoofed is my steed impelled by the spur;
The high sprigs of alder on thy shield;
Bran art thou called, of the glittering branches.”
“Sure-hoofed is my steed in the day of battle;
The high sprigs of alder on thy hand;
Bran by the branch thou bearest
Has Amataon the good prevailed.”
This master of Magick and poetry was also the cunning protector of his sister Aranrhod’s unwanted child, Lleu Llaw Gyffes. When his brother Gilfaethwy fell in love with Math’s footholder, Goewen, he organized a battle to get Math away from her. He did this by swapping some phantom horses with pigs owned by Pryderi and coveted by Math. When Pryderi discovered that the horses were not real, he marched on Gwynedd. While Math was away at war. Gilfaethwy seduced Goewen who was dismissed from her post when Math returned. Gwydion tried to have his sister Aranhod take her place but she needed to be tested for virginity using Math’s magick. When this happened she produced a baby named Dylan. Gwydion collected a drop of blood in a handkerchief at the same time and put it in a chest which developed into another baby, Lleu. Gwydion had to trick his sister into giving her son a name and weapons, apparently the duties of a mother. And Gwydion raised this child as his own.
But, Math was not pleased and needed to punish the two brothers. Gwydion and Gilfaethwy had deceived Math so he turned his nephews into a stag and deer for one year, into a boar and sow for the next and finally into a pair of wolves for the third before they could become themselves again.