The Abyssal walker is one of many monsters which can be found in the Abyss, and also in the Abyssal Area (Fairy Ring code: ALR). They are difficult to hunt as they seem to have a high defence, constitution, and strength, although they have low accuracy. It should also be noted that they are difficult to poison, although they are not immune to it. Abyssal Walkers killed in the Abyss yield much lower exp. These monsters are aggressive, but will stop being aggressive after a while as well as the Abyssal guardian and the Abyssal leech. They drop Abyssal charms fairly often, and two at a time, and are good to kill if seeking these charms for Abyssal familiars. They also have a reasonable drop rate for Green charms, which are also used in making the pouches for the abyssal familiars.
If hunting Abyssal monsters for their Runecrafting pouch drops, it is recommended to use magic against these. At relatively high defence and magic levels (70+) a player should have absolutely no trouble with them, even accounting for the aggressive monsters in the outer ring of the Abyss. It's recommended to use Mystic armour, and the highest level Air spell you can use, to cut rune costs.
It is common for players to train magic on these creatures, along with the other creatures found in the Abyss, as they are aggressive.