Forever Sleep
The Power of the All-Mother (or All-Father), also colloquially known as the Odin-Force, is a power granted to the ruler of Asgard which renders them near invincible, as well as allowing them to ultilise magic without the contraints normally placed even on Gods.
However, if the All-Mother overuses this power, they can be forced to enter a coma-like state known as the Foreversleep. (During Odin's reign this was usually referred to as the Odin-Sleep. While this name is sometimes still used, with the accension of Frigga to the throne, the older name began to be used again.)
While in the Forever Sleep, the All-Mother is no more invulnerable than any other Aesir, though they retain more awareness of the happenings in Asgard than if they were sleeping normally, due to the mystical bond between the monarch and their land. It is unknown if this awareness would continue if the All-Mother were to fall into the Forever Sleep while outside the Nine Realms.