Generates expanding waves of damage that radiate outward from the player. Two stats drive the wave's performance simultaneously: Projectile Speed controls how fast the wave expands across the field, and Duration controls how long each wave remains active. Stacking both scales the weapon from two independent directions — faster expansion covers more ground quickly, longer duration keeps the damage zone active through multiple enemy waves.

The damage is zone-based rather than projectile-based, so obstacles do not block the waves — they spread through the entire field equally. La Borra as the evolution material places Hydro Storm within the water-themed weapon chain: La Borra is the evolved form of Santa Water, and carrying it as an item while maxing Hydro Storm triggers the evolution.

Max Hydro Storm (Lv 8), carry La Borra, and open an elite-drop chest after 10:00 to evolve. The post-evolution weapon name is currently unconfirmed.

• Dual scaling through Projectile Speed and Duration allows reinforcement from two independent passive directions
• Zone-based wave cannot be blocked by terrain or obstacles — consistent coverage regardless of stage layout
• Expanding waves catch multiple enemies simultaneously as they spread outward through dense clusters
• Rune selection and Librarian purchase offer acquisition routes outside standard weapon offers

• Evolution destination currently unknown
• La Borra as evolution material requires obtaining and evolving Santa Water first — additional preparation overhead
• Two-stat optimization (Speed vs Duration) adds build complexity compared to single-stat scaling weapons
• Rune or Librarian acquisition limits availability compared to weapons in the standard weapon offer pool

• High Projectile Speed characters: faster wave expansion covers the field more quickly
• High Duration characters: longer wave persistence catches enemies in sustained damage over more time
• Imelda: +10% Growth levels Hydro Storm faster for earlier high-coverage performance

• Bracer: Projectile Speed increase accelerates wave expansion for rapid wide-area coverage (top priority candidate)
• Tome: Duration increase extends how long each wave remains active for continuous area saturation
• Spinach: +10% Might raises base wave damage independent of expansion or persistence
• Spellbinder: additional Duration stacking maximizes wave persistence for highest sustained damage

• XX Silent Old Sanctuary: Projectile Speed boost accelerates wave expansion further
• IX Divine Bloodline: crit compounding on wave hits raises DPS

• Early (0–10 min): Obtain Hydro Storm and level it. Secure both Bracer and Tome to build Projectile Speed and Duration simultaneously — expanding the wave's reach and lifetime from both sides early establishes strong field coverage quickly.
• Mid (10–20 min): Carry La Borra and push to Lv8 for evolution. With high Speed and Duration, position inside enemy clusters so the expanding wave continuously sweeps through the highest density zones.
• Late (20+ min): At peak Speed and Duration, waves rapidly expand across the full field and persist long enough to catch multiple enemy waves before expiring. Stay near incoming enemy flows to maximize wave-to-enemy overlap per cycle.

Q: How do I get Hydro Storm?
A: It is not a standard weapon offer — select it via Rune or purchase it from the Librarian. These are the only acquisition routes available.

Q: Should I prioritize Projectile Speed or Duration?
A: Both contribute meaningfully — stack them in parallel rather than specializing hard into one. Bracer and Tome are the natural pairing. Speed without Duration produces waves that expand fast but expire before covering the full field; Duration without Speed produces persistent but slow-expanding waves that leave gaps.

Q: What is La Borra?
A: La Borra is the evolved form of Santa Water (combined with Attractorb). For Hydro Storm's evolution, La Borra is carried as an item in the weapon slot — it must be an active weapon in your loadout when you open the evolution chest.