The demon horn necklace costs 35,000 Dungeoneering tokens and requires level 90 Prayer and 90 Dungeoneering to wear. The necklace was released along with a selection of eight other rewards, available at the rewards trader.
When worn, this necklace restores prayer points when burying certain bones:
The necklace is worth using in conjunction with the bonecrusher or attuned ectoplasmator in locations where monsters frequently drop bones, ashes, or are ghosts, as the combination can quickly restore Prayer points and no time is wasted manually burying the bones. While this is typically less useful at bosses, with sufficiently high damage output (especially with area of effect abilities like Dragon Breath, prayer renewals, and/or the penance aura) other methods of prayer restore may become unnecessary at bosses that drop high-tier bones or ashes like K'ril Tsutsaroth. This combination can also be helpful while fighting the Giant mole, as the mole summons groups of minions that drop bones.
Note that manually scattering ashes will not restore prayer points when using the necklace, nor will ghosts killed in conjunction with the ectoplasmator. Only ghosts killed or ashes scattered automatically by the attuned ectoplasmator will trigger the effects of the necklace.
The demon horn necklace used to be notable for having the largest prayer bonus of any item worn in the neck slot (+13), although since the Evolution of Combat the bone necklaces' bonuses were lowered to the point where the Dragon Rider amulet became the one with the largest prayer bonus, and even the cheaply available holy symbol and unholy symbol have larger bonuses.
After the quest Pieces of Hate, the Holy wrench boosts the amount of prayer restored from the Dungeoneering prayer necklaces by 10% as long as the wrench is either worn or in the inventory. For example, wearing the Demon horn necklace and killing an adult dragon restores 165 prayer points instead of 150 (a +10% increase).
90 
Armour
Life points
0
0
0
Silver
Expensive spices
Hazeel's mark
Robert's
Remora's
Shadows
Old
Charos
Brass
Clean
Shark's tooth
Mad
