Magni

Background
Magni, the brother of Modi, was the son of the Aesir god, Thor.

Ragnarok
During the battle of Ragnarok, Magni and his brother Modi defended Asgard against Surtyr and his army of frost giants from Jötunheim. After the realms were burned by Surtyr's flame, Magni rebuilt Asgard and became king.

The War Against Surtyr
After Ragnarok, Magni rescued the remaining Asgardians. He sent his brother, Modi, to find the giant Ortyr, to recruit him as commander of the Jotunn forces. After the watcher Heimdall returned from his exile in Vanaheim, Magni created a plan to get revenge of Surtyr and his army of fire giants.

With Heimdall back, the Vanir had joined them in their war. And Ortyr had command over the Jotunn army. The army arrived in Midgard where they met Surtyr. A battle erupted. Near the end of the battle, the Draugr king, Ferfeffnir attacked Surtyr and the Asgardians.

Surtyr was defeated, and the Draugr were pushed back when Heimdall killed Ferfeffnir.