The Berserker necklace is a melee necklace with no requirements. It gives +7 melee strength and +3 prayer, but −10 stab, slash and crush attack and −20 to every defence. On stats alone the free Amulet of strength (+10 melee strength, no penalties) is better. The necklace is worth wearing with an obsidian weapon, because together they raise your melee max hit by 20%. It is free from the Amulet & Rings shop at ::shops.
While you wear the necklace or its (or) version and wield one of the obsidian weapons below, your melee max hit is multiplied by 1.2, rounded down. It works against players and monsters. With a full obsidian helmet, platebody and platelegs as well, the obsidian armour bonus multiplies the max hit by another 1.1, so the necklace and the armour together give about 32% more max hit. Your equipment screen lists the necklace's bonus while you wear it.
Amulet & Rings shop: free. Talk to the Other Shops seller at ::shops and pick Amulet & Rings.
Variants
Item
How to get it
Value
Berserker necklace (or)
Use a Berserker necklace ornament kit on the necklace. It has the same stats and the same obsidian effect. Dismantle splits it back into the necklace and the kit (you need one free inventory slot). The kit costs 500 BHP in the Bounty Hunter shop and also comes from medium and master clue caskets. The (or) necklace is tradeable on the Trading post.