In order to access them you must have the corresponding key and 95 Slayer (90 with wild pie) is required to enter. They are known for dropping their signets, which are required to create the Ascension crossbow and its off-hand variant, powerful level 90 ranged crossbows.
The Legiones were created in 1890 AGS (roughly the Third Age) by Ocellus. Ocellus had breeded several ascended in his attempts to make strong humans that would worship no one, but failed. The ascended in these batches were either violent, insolent, or misguided. Ocellus noted that the leaders he made were either too powerful, intelligent or unstable, which resulted in him having to punish or liquidity them. Ocellus hoped that if he linked their minds together, they would think as one. Ocellus went forward with this idea, and called the resulting ascended as Legiones. It is unknown how many Legiones were created (and what happened to them); regardless, there are seven known Legiones during the Sixth Age.
In 1902 AGS, Ocellus remarked how the Legiones were creative with their minds, as they accelerated crystal production throughout the whole complex, as it was too much for Ocellus to handle. Sometime in 2167 AGS (Fifth Age), Ocellus found the Legiones leading a prayer to Guthix. Ocellus attempted to punish them, but the Legiones resisted. He later told them what they did was wrong, and that it was not what Guthix would have wanted.
During 2167 AGS (beginning of the Sixth Age), the Legiones were aware that Guthix was killed and went into denial. The Legiones could not imagine a life without Guthix, and decided to create an artifical, ascended Guthix. While Ocellus admired their ambition, he saw their objective as misguided and attempted to explain their error to them. Ocellus confronted them again, only to be defeated, so he stayed outside the complex to prevent any Ascended from leaving.
The Legiones currently reside in their labs, attempting to find out ways to ascend man into godhood. In order to reach them, players must kill their fellow members (Rorarius, Gladius, Capsarius or Scutarius) to get a key which will unlock one of their labs.
One of the Legiones, Legio Septimus, left the group, calling the other Ascended "idle fools" as they did nothing but feed on the crystals in the caverns. He led his group of Ascended and allied with Nomad to create a new Guthix.
- Although the Slayer tab says that a Slayer level of 95 is required to fight the Legiones, they do not have a Slayer level at all, as players of a lower level doing Co-op Slayer can still harm them. 95 Slayer is only required to open the door, and if the boosted level wears off mid-fight they will still be able to damage the Legione. However, the lowest possible level to attack a Legio without the Slayer requirement is 76 using a wild pie, as entering the Monastery requires a Slayer level of 81.
- Legiones are one of the very few monsters in RuneScape whose attacks are only slightly reduced by protection/deflection prayers instead of being reduced by 50%.
- For a while after the Crystal Triskelion was released, the Legiones were unable to drop crystal triskelion pieces despite their slayer level being high enough to meet the requirement. This was soon fixed in a later update.