Siren Strongholds are demanding Operation Siren maps with multiple fights and reward nodes. Build Adaptive Tuning through easier zones first, then enter when your fleets can handle the Stronghold’s Corrosion level. Use a mob team for routine encounters and a stronger boss team for the final fight; ships retain damage between battles. Complete the map and collect the available rewards, including any materials that feed Gear Lab progression.
Unlock Operation Siren and reveal the Stronghold location.
Raise Adaptive Tuning to at least the entry’s stated minimum.
Prepare distinct fleets for ordinary encounters and the boss.
Bring repair and recovery resources appropriate to your fleet’s condition.
Check the Stronghold’s Corrosion level and entry requirements on the map.
Clear lower-level Operation Siren zones to improve Adaptive Tuning if needed.
Review fleet health and equipment, then assign a durable mob fleet and a capable boss fleet.
Enter the Stronghold and defeat its encountered Siren fleets in sequence.
Collect reward nodes and map loot as you advance rather than leaving them behind.
Defeat the final boss and claim the completion rewards.
Review materials and tuning progress, then decide whether another available Stronghold or coordinate target deserves your resources.
Farming tips
Keep each fleet’s role clear: a healer can reduce attrition in the mob fleet, while the boss group should prioritize dependable damage and survival.
Enter with tuning at or above the displayed Corrosion requirement; extra tuning beyond the game’s cap does not provide additional benefit.
Repeat, collect and use
Stronghold availability is tied to the Operation Siren monthly cycle and map state. Complete each available Stronghold for its rewards; do not assume it can be endlessly repeated for identical loot.
Common mistakes
Entering with insufficient tuning; raise it in lower-Corrosion zones first.
Using a weakened mob fleet against the final boss; check damage and recover between fights as available.
Leaving reward icons uncollected; sweep the map before exiting.
When to stop or switch
Stop once the available Stronghold is complete or your fleet condition makes further fights inefficient; shift to recovery, tuning, or easier map objectives.
