These can be killed at level 35 Slayer. They give 105 Slayer experience per kill. Wall beasts have high Constitution and relatively low stats. They are fairly good for training Ranged and Melee at low levels, due to their Defence being very low. Unlike other monsters they cannot be poisoned. Their charm drop rate is fairly high, so it's good for gathering charms.
A spiny helmet is needed to kill these, or heavy damage will be taken. The monster is actually in the wall, so watch out for cracks in the caves.
A big scary hand!
Clue scroll (level-2)
Coins (15), Bronze med helm, Bronze full helm, Iron med helm, Steel full helm, Steel med helm, Mithril med helm, Mithril full helm, Adamant med helm, Cosmic rune (2), Chaos rune (3-7), Nature rune (2), Air rune (3-5), Tinderbox, Bullseye lantern, Lantern lens, Unlit torch, Eye of newt, White mystic hat, Crimson charm, Green charm, Gold charm, Blue charm, Grimy herbs