Lagu is another journey rune, this one of the sea. It is to Sigel, what Eh is to Raed. It is the rune of the rough passage, of the terrifying transformation. An alternate name for this rune in the Proto-Germanic is Laukaz or the leek. Leeks are known for their rapid growth and are sacred to the god Thunor (Thor). Here again we see the North Sea storm symbolism for Thunor is god of the Thunderstorm. Lagu, therefore refers to rapid uncontrolled change which if geared towards growth can be helpful, but if allowed to go astray may lead to destruction. Leeks were also used for healing though, and this is Lagu's good aspect. Physical healing in and of itself can be a rapid though controlled process like the growth of a leek, and rapid change if controlled can lead to great progress for any undertaking.

Lagu's name means "sea" and this indicates that the rune itself may have links to Wyrd. Much of the water symbolism in Norse Mythology was tied to the concept of Wyrd (see Bauschtaz), and the rune Lagu is perhaps no different. Lagu may refer to one caught in the results of their own deeds, caught in their own wyrd, being tossed about like an uncontrolled ship on the ocean. Lagu may then be those times in life of great travail, bankruptcy, divorce, family deaths, things that often seem beyond our control.

In divination, Lagu can indicate rapid change good or bad. In spellwork Lagu can be usedto promote growth and healing, but one must be careful to control these processes. A safer rune to use for such things is Beorc.