Although there are many motifs in this story, such as birds, kin killing, and mutilation of horses, but the most reacuring moif i noticed was magic. This motif appears several times through out this novel and literature.
The first example of the use of magic is the cauldron of reserection. It has the power to reserect the dead when that person is lade down in the cauldron. Malthowych tells Bendigeidfran of two poeple who had the cauldron. After these two people left the Kingdom of Malthowych, as bad terms, they ended up at Wales, which is how the Cauldron got in the possesion of Bendigiedfran. He he gave it to Malthowych to repay him for what his brother Efnisian did to his horses.
Branwen uses her power to to train a bird for three years to find Bendigeifran and tell him she was being mis-treated by Matholwch. Without this message, Bendigeifran would not have been known anything about this disrespect to his family, which brings me to the next example. After Bendigeifran heres whats happening to his sister, he is enraged. He uses his power to become a giant and wade across the water passage with his entire army. The people of ireland thought it was a mountain crossing the water, and they thought the ships was a large moving forest.
Bendigeifran, and his 4 brothers and sister poses powers, there mother is known to be a farry, which is where they obtain these abilities.