Diamond staff

Diamond staff is a two-handed staff that requires a Magic level of 65 and a Slayer level of 70 to wield. It can be bought from any Slayer Master for 148,000 coins.

It is mainly used to cast the Diamond Rain and Diamond Barricade spells, which are the only magic spells that can damage the Metallic experiments, and one of three weapons used to damage the metallic experiments, the other two being the diamond longsword and the diamond twinhammers. Asides that, the staff is mainly used to fight metallic dragons and other monsters weak to magic, as the diamond spells are very powerful against them.

Special Attack
The special attack of Diamond staff is called Shatterglass. It consumes 50% adrenaline. It deals 100-180% active spell damage. If it succesfully hits the target, it reduces its target's Attack, Ranged, Magic, Strength and Defence by 10% of the damage dealt. Against a monster, it decreases its Magic defence by 10% and the target's affinity values are increased by 2 for 1 minute. The attack also has a higher chance of hitting the target. It was released after Evolution of Combat to balance the lack of magic weapons with special attack.

History and market
Diamond weapons were released alongside the 120 Slayer expansion. During its release, Diamond staves' price started at its shop price at 148k, but its price quickly rose to 500k due to its demand as a powerful magic weapon as well as being a weakness to metal dragons, which meant that the weapon had demand for PvMers and PvPers alike. This was however countered by the fact that Diamond staves could be bought for a fixed price from the Slayer Masters, causing the weapon's price to drop to its shop price after the initial hype was over. While further updates did improve its uses, unlikes diamond longsword, its price did not change drastically due to its availability. Even after a hidden update caused Diamond staff to deal 10% more damage while fighting metal dragons, its price only spiked for a short period of time before returning to its default value. After Evolution of Combat, the prices of diamond staff nonetheless crashed, due to having its effectiveness against dragons removed and becoming overall less effective weapon than cheaper, higher-level weapons such as Ahrim's staff, causing the diamond staff's price stabilized above its High Alchemy price. Further updates caused the weapon's Grang Exchange value to eventually rise, but it never reached its old value.