The Short Answer

Take a regular Enchant Relic to Keeper's Altar at night. Equip the rod you want to change, hold the relic, and interact with the active altar. The relic is consumed and applies a random regular enchant, normally replacing the rod's current regular enchant.

Get a Regular Enchant Relic

Enchant Relic in Fisch
Enchant Relic renderImage source · Community Wiki ↗
Enchant Relic Bestiary view in Fisch
Enchant Relic Bestiary viewImage source · Community Wiki ↗

Relics can be fished from the normal catch pool, found in Treasure Chests, or purchased from Merlin at Sunstone Island after level 30. The August 25 Wiki entry lists a single relic at 11,000 C$. Special relic types use different enchant pools.

Reach Keeper's Altar

  1. Go to the Statue of Sovereignty and enter the Sovereignty Mines.
  2. Pay Cole the normal 400 C$ elevator fee unless you already have permanent access.
  3. Ride down to Keeper's Altar.
  4. Wait until night; the regular altar is not active during the day.

Apply the Enchant Safely

Large Enchant Relic example in Fisch
Large Enchant Relic exampleImage source · Community Wiki ↗
  1. Equip the exact rod you want to enchant.
  2. Check its current enchant before continuing.
  3. Hold the regular Enchant Relic and interact with the active altar.
  4. Confirm the result after the relic is consumed.

Why It Says Not Working

The usual blockers are daytime, the wrong rod equipped, the relic not held, or being at the wrong interaction point. If the altar works but you dislike the result, that is not a bug—the outcome is random. Do not roll again casually: another regular relic can replace a useful enchant. For the nearby purchase route, see how to get King's Rod.