If you intend to keep it as one of your permanent skills, then you’ll want to look into getting the Eel Tongue Legendary Weapon, as it will increase Bone Spirits.

It has a half a second cooldown so its a good skill to use in between your primary attacks. Runewords convert Armor or Weapons in Unique Equipment once the required amount of Runes is placed in the correct order, granting said item a fixed set of properties. It allows you to summon a wave of bone spirits which deal x damage to nearby enemies.

Spirit can be used in the following equipment: In order to create Spirit you need to socket these Runes in the following order:

Adds 3-14 Cold Damage 3 Second Duration (Normal).

Spirit grants the following modifiers: Weapons It is sought after by many players and is considered a valuable addition to any character's arsenal. The spirit runeword is crucial for spellcasters, as it helps them reach their full magical potential with faster casting speeds and increased mana regeneration. Additionally, the runeword gives the player enhanced defense and provides a higher chance of blocking attacks. When crafted, this runeword provides several benefits, including a +2 bonus to all skills, +25-35% faster cast rate, and +55% faster hit recovery. It requires a four-socketed sword or shield and the runes Tal and Thul, Ort and Amn. The Spirit Runeword can be applied to Shields and Swords and is composed of 4 Runes. Diablo 2's spirit runeword is one of the most popular and valuable runewords in the game.

Bone spirit diablo 2