Is it possible to unlock the weapon in a single run?

Yes, the guide states that a modifier can be used to make all three minibosses spawn in a single run.

What is the reward for completing the quest?

The reward is the 'Fish Deity's gun,' a powerful aquatic weapon that is available for all future runs.

Abyssus Aquatic Weapon Guide

Aug 16

The aquatic weapon in Abyssus is hidden behind the Secret Pond event, one of the most obscure unlocks in the game. It is not tied to the main story, and many players miss it because the steps require multiple runs. By completing the Mystery of the Pond quest, you unlock the aquatic weapon, often referred to as the Fish Deity’s gun, for all future playthroughs.

The aquatic weapon is unlocked by completing the Secret Pond event and defeating the Fish Deity.

How to Unlock the Aquatic Weapon

Defeat the Three Miniboss Variants

In Act 4 Stage 1, three miniboss variants spawn before the Royal Abyss. Only one appears per run. Each miniboss corresponds to a guardian statue in the lobby fountain.

Defeating one will activate its matching statue. You must defeat all three across separate runs to fully awaken the pond.

Activate the Secret Pond

When all three statues are spewing water, return to the Pregame Lobby. Behind the waterfall on the seaside path is a hidden room.

Inside, wait until the pond fills completely. This will trigger the Fish Deity event.

Claim the Aquatic Weapon

Defeat the Fish Deity in the Secret Pond to earn the aquatic weapon. Once unlocked, it becomes available in all future runs.

Tips for Unlocking Faster

Use a modifier to force all three minibosses to spawn in one run.
Keep track of which statues are already active so you don’t waste time repeating kills.
Some minibosses, like the frog variant, are easier to clear quickly, saving resources for the final fight.

Click here to see all weapon unlocks.

Final Blurb

The Abyssus aquatic weapon is one of the game’s best hidden rewards. By defeating all miniboss variants and activating the Secret Pond, you can unlock the Fish Deity fight and claim this powerful weapon. It takes patience, but once unlocked, it stays available for every run.

FAQ

How do you unlock the aquatic weapon in Abyssus?

Defeat all three miniboss variants in Act 4 Stage 1, activate the lobby statues, then enter the Secret Pond behind the waterfall to fight the Fish Deity.

What is the aquatic weapon reward?

It is the Fish Deity’s weapon, also known as the Fish Gun, which becomes available for all future runs.

Can you unlock the aquatic weapon in one run?

Yes, but only if you use a modifier that forces all three minibosses to appear in Act 4 Stage 1.

Do minibosses need to be killed in order?

No, any order works as long as all three statues are eventually activated.

Where is the Secret Pond located?

It is hidden in the Pregame Lobby, accessed by going behind the seaside waterfall once the statues are active.