Clayman's Harpoon is a Spear in Elden Ring. The Clayman's Harpoon scales primarily with Strength, Dexterity, and Intelligence and is a good Weapon for its additional magic damage.  

Elden Ring Clayman's Harpoon Notes & Tips

• Weapon Skill: Impaling Thrust
• This weapon can be infused with Ashes of War
• Clayman's Harpoon can be upgraded by using Smithing Stones
• Can be buffed with Magic and Consumables.
• Sell Value:  

   100

• Base drop rate is 2% (at 100 Discovery).
• A versatile weapon that can be useful for Strength Intelligence builds, pure Intelligence builds and Intelligence Faith builds depending on the infusion.
  
  • When infused with Heavy infusion, it offers A scaling for Strength.
  • When infused with Magic infusion, it offers B scaling for Intelligence while the damage scaling is primarily applied to magic damage, making it a good weapon for casting Ashes of War that inflict magic damage, such as Glintstone Pebble, Glintblade Phalanx, Ice Spear and Loretta's Slash.
  • When infused with Cold infusion, it offers 105 Cold buildup and C scaling for both Strength and Intelligence. Since the damage scaling is primarily applied to the magic damage, this makes Cold Ashes of War such as Chilling Mist, Ice Spear and Hoarfrost Stomp especially effective.
  • When infused with Flame Art or Sacred infusion, it offers B scaling for Faith and D scaling for Intelligence while simultaneously offer dual elemental damage outputs.
• Note: As of Patch 1.08, poise damage of all Spears has been reduced for PVP.
• NOTE: As of Patch 1.09, the scaling values of this weapon were changed. Please refer to the Upgrades Table of this weapon below.