Heimskringla Black Magic

Vísburr took over the inheritance after his father Vanlandi. He got the
daughter of Auði inn auðgi (the Wealthy) in marriage, and gave her as
bride-price three large estates and a gold necklace. They had two sons,
Gísl and Ǫndurr. But Vísburr abandoned her and took another wife, while
she went to her father with her sons. Vísburr had a son called Dómaldi.
Dómaldi’s stepmother brought misfortune on him with a spell. And when
Vísburr’s sons were twelve and thirteen years old, they went to see him
and claimed their mother’s bride-price, but he would not pay it. Then they
said that the gold necklace should cause the death of the best man in his
family; they left and went home. Then more black magic was brought
into play, and a spell cast that would enable them to kill their father.
Then the witch Hulð told them that she would bring this about by spells,
and along with it that there would always be killing of kindred in the line
of the Ynglingar after that. They agreed to this. After that they gathered a
troop and took Vísburr by surprise at night and burned him in his house.
So says Þjóðólfr:

7. And Vísburr’s
vault of wishes
the sea’s kinsman
swallowed up,
when the throne-defenders
the thieving scourge
of forests set
on their father;
and in his hearth-ship
the hound of embers,
growling, bit
the governor.

[...]

Dómaldi succeeded his father Vísburr, and ruled his lands. In his time there
was famine and hunger in Svíþjóð. Then the Svíar held great sacrifices at
Uppsalir. In the first autumn they sacrificed oxen, but even so there was no
improvement in the season. The second autumn they held a human sacrifice,
but the season was the same or worse. But the third autumn the Svíar came
to Uppsalir in great numbers at the time when the sacrifices were to be
held. Then the leaders held a council and came to an agreement among
themselves that their king, Dómaldi, must be the cause of the famine,
and moreover, that they should sacrifice him for their prosperity, and attack
him and kill him and redden the altars with his blood, and that is what they
did. So says Þjóðólfr:

8. Once it was
that weapon-bearers
with their ruler
reddened the ground,
and the land’s people
left Dómaldi
without life,
their weapons bloody,
when the Svíar
seeking good harvests
offered up
the enemy of Jótar.


- Heimskringla, Ynglinga Saga, Chapters 14 and 15