Little Mermaid (Siren) Guide & Review

Can you give a brief summary about this unit?

Siren is an awesome B1 unit who can provide reliable CDR, ATK DMG▲, and Damage Taken▲ while personally contributing a large amount of sustained damage. She can stun enemies, which is useful situationally, and allows the team to focus-fire outside Full Burst. These are QoLs that seem trivial but can be game-changing for mobbing and clearing QTEs. The stun also opens up new strats in PvP, allowing you to stun enemy critical PvP units and interrupting their burst chain.

At first glance, she is just a sidegrade of Rapi: Red Hood in the B1 position, slightly better if any due to her having more damage and scaling potential. While she is versatile and can fit in many teams, her DPS scales with the team's total attack speed, meaning the more MGs are in the team, the more damage she will land. She also complements their lack of burst gen through instant fills every certain number of shots.

Being a Wind element herself, she shines against Wind-weak Bosses in general such as Kraken in Anomaly Interception. With proper investments, she can rival the damage of Scarlet: Black Shadow and even Asuka: WILLE. She also handles neutral elements well and goes toe-to-toe with Rapi: Red Hood depending on team composition. This makes her an irreplaceable/meta unit for both Union and Solo Raids.

She is also strong in Campaign thanks to her focus-fire and stun, and her presence also allows for new team formations involving Rapi: Red Hood as the primary B3. She might as well be the best B1 for Pilgrim Tower too! In PvP, she has demonstrated potential as a burst chain interruptor — similar to Soda — echoing the new trend that's been gaining traction recently.

Overall, she is an excellent all-in-one B1 package for all intents and purposes.

Should I get this unit?

Indubitably yes. She is a Pilgrim with a 1% chance of appearing, and although to some people her performance can be a little disappointing because she is not as groundbreaking as Crown was, she is still terrific. In fact, she outright replaces Rapi: Red Hood in some comps against certain bosses thanks to her having more outlined advantages and disadvantages.

Missing a 1% unit in their rate-up can be fatal since the chance of obtaining her later on will be outrageously slim. Hence, skipping is not an option. As usual, we recommend using Gold Mileage to avoid spending too many pulls on a 1% unit, even with the rebate event going on at the moment. Despite that, you can still pull if you want, but remember those reward steps in the event are sequential and not cumulative. That aside, dupes are not necessary due to her lack of team ATK▲ buff but are welcome for overall personal damage and CP padding.

Siren wields an SMG that shoots up to 24/s in 60 FPS with Min Firing Rounds Requirement (new setting) turned on. However, this only applies to PvE and Rookie Arena; she still shoots 15/s in Special Arena and Champions Arena. This PVE change makes her base uptime per magazine 5 seconds with a base reload time of 1 + 0.367 second. Her burst generation value sits at 0.1% per shot. Like most other SMGs but unlike other weapons, she has 250% core damage.

Skill 1

■ Activates only when in Focusing status. Affects all allies.

Focuses fire continuously.

■ Activates when Full Burst ends. Affects all allies.

Cooldown of Burst Skill ▼ 7.48 sec.

■ Activates when entering Full Burst. Affects all allies.

Attack Damage ▲ 4% for 10 sec.

■ Activates each time total ammo consumed by allies reaches 400. Affects all allies.

Fills Burst Gauge by ▲ 37%.

• Whenever Siren is alive and whenever you are manually controlling her aim, Focus Fire automatically activates, allowing you to direct your team's aim outside Full Burst as if you were in Full Burst.
• This is useful for certain edge cases when focus-fire is necessary outside Full Burst, such as for mobbing and clearing QTEs. It also helps with forcing units to to hit ideal parts of a boss, like its core.
• It also helps with forcing Machine Gun units to stay firing, avoiding wind down due to AI taking cover when enemies are not present.
• Since normally you want to be in Full Burst all the time, this effect, while noticeable, should not provide too drastic of real-world impact in regulated runs where timing randomness is kept to minimum (except when focus-fire is a crucial aspect of a strat).
• Besides that, you cannot manually control Siren when you need to spam/quick-shot other units for burst gen (if you use SRs/RLs).
• Whenever Siren is alive and a Full Burst ends, Siren will reduce all Burst Skills' CDR by 7.48 sec.
• Same value as Rapi: Red Hood's.
• Instant and dependable without rigorous activation requirements; great for Campaign where sometimes all units must take cover.
• High value, allowing her teams to scale on rotation speed. Faster = more damage. Complemented by her Instant Fill ability.
• Siren also increases the team's ATK DMG by 4% for 10s when entering Full Burst.
• The value is small but the impact is noticeable, especially with units with low starting ATK DMG (and same-category buff) values.
• Can be triggered off-burst, which means the buffing still takes place even if Siren is not Bursting. This can allow synergy with units like Red Hood B1.
• Siren also recharges Burst Gauge by 37% when the total ammo consumed by allies reaches 400.
• Complements naturally slow teams without battery, so Siren can be paired with more MGs and trigger her damage skills more often.
• However, it is optional, and Siren can still be run with a battery unit. In fact, you can run Siren without MGs if needed despite lowering her personal damage because she is still versatile.
• Does not count Infinite Ammo like Grave's and Modernia's Burst Skill.
• Shotgun is treated as “one ammo consumed” although they shoot a lot of pellets.
• Ammo counting still happens inside Full Burst, so your next fill after Full Burst ends will be between 1~400 ammo away depending on timing.
• Without battery units, will need around ~2 Instant Fills to charge fully from zero having accounted for each unit's own burst generation.
• Like Helm Treasure's S1, it is not affected by Quantum Cube.

Skill 2

■ Activates when the enemy appears. Affects the target.

Bubble: Damage Taken ▲ 5.05% continuously.

■ Activates after landing 50 normal attacks(s). Affects the target if the target is in Bubble status.

Explosive Bubble: Damage Taken ▲ 5.05% continuously.

Stuns for 3 sec. Removes Bubble.

■ Activates every 1 sec only during Full Burst. Affects random enemy unit(s).

Deals 63.36% of final ATK as damage. Attacks sequentially for 4 time(s).

■ Activates each time total ammo consumed by allies reaches 500. Affects random enemy unit(s).

Bubble Barrage: Deals 85% of final ATK as damage. Attacks sequentially for 10 time(s).

• Whenever an enemy appears, regardless of whether it is a Rapture or a Nikke, they are immediately inflicted with the debuff “Bubble”, which explodes upon receiving 50 normal attack(s) from Siren, stunning them for 3s. The debuff then ‘evolves’ into “Explosive Bubble”.
• Both Bubble and Explosive Bubble make the enemy take 5.05% more damage permanently.
• Damage Taken▲ debuff category is rarely diluted, and because of that, the damage improvement can be considered reliable and stable and more noticeable.
• It may be better in Solo Raid to pair her with characters that already have diluted ATK DMG▲ and ATK▲ category because it is more difficult to scale them further.
• During Full Burst, every second, Siren will attack sequentially 4 time(s), for a total 40 hits. Siren will also attack sequentially 10 time(s) every time total ammo consumed by allies reaches 500.
• Sequential attacks work by selecting random enemies to create a cycle, and attacks are done in order (except when taunted, making the taunter the first enemy to be hit). The same unit will not be attacked twice unless there are not enough unique enemies.
• When there are not enough unique enemies (fewer than sequential number), the cycle will repeat, and the enemies that were hit early in the first cycle will be hit again. This means if there is one enemy, that enemy will take all hits.
• Both sequential attack(s) together create high AoE clearing potential, allowing Siren to deal damage to multiple enemies at once while her teammates focus on just one target. This can be particularly useful against Harvester in Anomaly Interception.
• Not that effective in PvP due to low FPS in Special Arena and Champions Arena.
• Shotgun is treated as “one ammo consumed” although they shoot a lot of pellets.
• Siren’s sequential attacks are her main source of damage, and she deals a lot of damage because they have high multipliers. Siren does not have a lot of personal offensive buffs, which means she is highly scalable and scales with external buffs better.
• Compared to Dorothy, Dorothy’s Distributed DMG has similar percentage values (slightly less if Siren is well supported), but the reason for the huge difference lies in the difficulty of buffing Dorothy’s Burst Skill damage. It snapshots buffs upon use, and usually there aren’t many buffs active before B1’s Burst Skill. On the other hand, Siren’s damage updates dynamically.

Burst Skill

■ Affects all allies.

Attack Damage ▲ 10.13% for 10 sec.

Reloads 33.26% magazine(s).

■ Affects self.

ATK ▲ 17.28% of caster's ATK for 10sec.

• Siren Burst is on the weak side and has a meager Attack Damage value. However, it still has a noticeable impact.
• One noteworthy thing is that she provides Ammo Refund, which is great for most MG users. Pairing it with Bastion will allow your MG to shoot even longer before she needs to reload.
• The general formula for Ammo Shot = Your Ammo/ (1-(Bastion ammo/10))*(1-%Ammo Refund).
• Ammo Refund synergizes well with Max Ammo▲ buffs, and while it is neither synergistic nor antagonistic with Reload Speed▲ (though less efficient if you pair them together), it still increases uptime and therefore results in higher output. There is nothing wrong with pairing Siren with Crown.
• Siren will also grant herself a small amount of ATK buff, which improves her damage, but it’s nothing too impressive.
• This makes Siren’s Burst Skill not mandatory to use, and you can use other B1’s Burst Skills if you want, like Red Hood in Campaign. However, for minmaxing in Raids, or when the circumstances allow, running 1-1-3 (or 1-2-2) is usually more effective and efficient.

Campaign (LD) - SSS | Campaign (HD) - SSS

With instant 7.48s CDR, Siren is immediately placed in at least SS tier B1 no matter which mode besides PVP. But, she’s more than that. She’s an okay tier DPS with a moderate amount of offensive buff, and she allows you to run Rapi: Red Hood as B3 (which she’s intended to be). Her split damage can come in handy in some stages, but most of the time, you just need her to be there, so your Rapi can destroy everything.

In high deficit mode, her forced focus-fire assists with dealing with mobs with a low HP but a deadly output like Starfish or Bullwhip. Her stun can even stop Bronchus (Fart Rapture) for 3 seconds too, giving you more time to take them down (or enter the next Full Burst cycle). Furthermore, she has a special use against Crystal Chamber, which you fight a lot, where her focus-fire can help you break its hitcount rock and QTE phase even without Full Burst.

Compared to Rapi: Red Hood B1, Siren slightly falls behind in Glass (mob with hitcount shield) clearing potential. She also does not have team ATK▲ buff, which can be a problem in higher deficits.

Siren can also be paired with Red Hood B1 in the 2-1-3* formation (Red Hood can B1 or B3). Since ATK▲ buffs are very important in Campaign and Siren’s Burst Skill is pretty lackluster, there is no harm in using other B1’s Burst Skills. In fact, it will actually improve Siren’s personal output too.

Siren is probably the best B1 for Pilgrim Tower at the moment as she allows Rapi: Red Hood to B3, can pair with Red Hood B1, and scales well with Crown (ATK buff, MG). No more suboptimal Dorothy runs!

Bossing - SSS

Nuff said. For a B1, she surely deals a lot of damage compared to our traditional supporters. This will compensate for her weak supportive offensive buffs. Still, you would need to form a proper high Fire Rate team for her, else she’s just another CDR without anything special. With proper units to support her (ATK/ATK DMG buffs, ammo usage, etc), she shines and provides much more impact than Rapi: Red Hood damage wise.

Additionally, her usage will skyrocket against Wind-Weak bosses. Whereas Rapi:RH is strong against Wind and Electric, Siren is strong against Iron. Moreover, most of Siren’s damage is not from basic attacks but from her sequential (ammo usage count). This makes her less reliant on the existence of core/parts and better tuned to modern bosses.

We have a lot of screenshots showcasing Siren matching SBS on A.I. Kraken (but, realistically, Siren damage will be around 50~60% of SBS max, assuming both SBS and Siren share the same amount of investment).

PVP - S

The fun part of using Siren is how she can stun a target she shoots the 50th bullet at without having to Burst (unlike Rapunzel, Soda, or Privaty). Depending on mode and setting (Rookie Arena with Min Firing setting will allow Siren to shoot faster), Siren can strategically disable a key target, leading to overwhelming advantage. This can be used to block enemy Burst Chain, force enemy to use a different “less ideal” Burst Skill, or delay their attack/buy time for your team to kill the enemies first. Be careful, however, because in some cases if you are very unlucky, you might stun an enemy AoE wiper (esp. with Blanc) and allow them to delay their attack until your Noah immunity drops, ultimately helping the enemy instead of your team.

In Rookie Arena with setting on, Siren will be able to stun enemy B1 usually before their B1 @ 2 RL is used. In Champion and Special Arena, Siren will start stunning her first target slightly before 3 RL (when 0% charge speed RL shoots its 3rd ammo). This can sometimes block B2 and usually will block B3. For example, Scarlet Trina Rumani Jackal Centi won’t be able to Burst because Scarlet will be stunned before she can Burst. However, whether you can catch them varies depending on the enemy’s Charge Speed.

More team setups showcasing Burst Skill usage redirection are in the PvP Team Compositions section.

Gear Investments

Siren is a supporter, and since she does not have any team ATK▲, if you only care about her supporting capacity, then she does not need any specific lines. You can even use her without OL!

However, if you want to optimize her personal damage, you should definitely get ELE and ATK lines, with Crit Rate/Crit Damage as flexes/3rd option or Max Ammo (for uptime, triggering S1/S2 more often). Just keep in mind that her damage may not match your expectation outside her specific element with all the investments you poured into her, and Mihara is near (and Mihara also wants OL investments). Manage your rocks well.

• Essential: -
• Ideal: 4× ELE, 4× ATK
• Passable: 4x Crit Rate, 4x Crit Damage, 1~2× Max Ammo
• Priority: High

Skill Investments

Of course, if you want to improve her damage, you will want to go 10/10/10 immediately, but there are a few compromises you can make depending on your objectives:

• Skill 1: 7~10
• This is her most important utility: Cooldown Reduction! Stopping at Lv. 7 is fine on a slow-to-normal team, but you can push this to Lv. 10 for very fast rotation teams.
• Skill 2: 7~10
• Where her multipliers lie. Push this skill to 10 if you want to build her DPS. With the new improvement in Simulation Room’s reward, having skills at Lv. 7 is not as painful as before.
• Burst Skill:4~10
• Her Burst buff is meh, so 7 is okay. But, damage is damage. Max this if you want the most damage out of her and your team. Less important if you use her as alternate B1, which is something you can do for campaign mobbing.

Suggested Progression Path

 

PVE Investment

PVP Investment

Priority

Little Mermaid (Siren)

PVE investment

1/1/1 → 4/4/4 → 7/7/7 (→ 10/10/7)

PVP investment

1/1/1 → 4/4/4 → 7/7/7 (→ 10/10/7)

Priority

Meta

Cube Investments

When Elemental Advantage is concerned, use the highest level cube available. Otherwise, Bastion or Resilience (with Reload Speed comps) would suit her well, but in the end it does not matter much because her auto-attack damage is negligible.

Doll Investments

Consider giving her SR 5 for the 5×5 Quest. Other than that, they are mainly for CP padding, which is important in Campaign, Pilgrim Tower, and PvP. Damage Taken reduction is useful too.

Team #1: Basic Siren comp

Burst 2

Burst 1

Burst 3

B3

Burst 3

B3

Burst 3

The basic comp for Siren, featuring the backbone Crown - Helm - Siren and 2 more DPS based on situation. This team can run on Campaign, Bossing, AI too.

Team #2: Pillaging the Harvester

Burst 2

Burst 1

Burst 3

Burst 3

Burst 3

This comp is tailored for A.I Harvester. Depending your Helm/Xlud, you will want to burst them. Rapi should be B3 here, with either Helm or Xlud act as non burst DPS. Just pay attention if you want to burst with Helm, her burst will hit normal mob so clear them first.

Team #3: Release the Kraken

Burst 2

Burst 1

Burst 3

Burst 3

Burst 3

Another version to deal with A.I Kraken. Pretty much controlling Siren and just aim the core. Trying to break 4 first tentacles as soon as possible to reach phase 2 for permanent core uptime.

Team #4: Ultra Pro Max

Burst 2

Burst 1

Burst 3

Burst 3

Burst 3

For Ultra, you can run this one. Replacing Helm with... Helm Summer version if you have her S2 at lv 10. Again, reaching phase 2 asap to access core easier.

Team #1: Don't let her burst

Burst 3

Burst 2

Burst 1

Burst 1

Burst 2

The new PVP comp featuring Siren. She can cheese P1 around 2 or 3 RL depending which mode you are playing. But this will be extremely effective when you fight Noah P1, because Siren will stun her no matter what.