| Type | Icon | Name | SP | Required | Description |
|---|---|---|---|---|---|
| A | 
|
Water Boost 1 | 50 | — | At start of combat, if unit's HP ≥ foe's HP+3, grants Res+2 during combat. |
|
Water Boost 2 | 100 | Water Boost 1 | At start of combat, if unit's HP ≥ foe's HP+3, grants Res+4 during combat. | |
|
Water Boost 3 | 200 | Water Boost 2 | At start of combat, if unit's HP ≥ foe's HP+3, grants Res+6 during combat. | |
| No restrictions. | |||||
Available as a Sacred Seal.
Notes[ | ]
- The stat increase that can be applied by Water Boost is considered a temporary buff.
- Water Boost compares current HP between units to apply the temporary buff.
List of owners[ | ]
| Unit | Skill chain | |||
|---|---|---|---|---|
 | Water Boost 1 3  | Water Boost 2 4  | Water Boost 3 5  | – |
 | Water Boost 1 5 | Water Boost 2 5 | Water Boost 3 5 | Fireflood Boost 3 5 |
 | Water Boost 1 5 | Water Boost 2 5 | Water Boost 3 5 | Deluge Boost 3 5 |
 | Water Boost 1 5 | Water Boost 2 5 | Water Boost 3 5 | Fireflood Boost 3 5 |
 | Water Boost 1 5 | Water Boost 2 5 | Water Boost 3 5 | Fireflood Boost 3 5 |
 | Water Boost 1 3 | Water Boost 2 4 | Water Boost 3 5 | – |
 | Water Boost 1 5 | Water Boost 2 5 | Water Boost 3 5 | Fireflood Boost 3 5 |
 | Water Boost 1 5 | Water Boost 2 5 | Water Boost 3 5 | Fireflood Boost 3 5 |
* 
Alfonse: Prince of Askr, Sharena: Princess of Askr, Anna: Commander, and Forma units cannot be used for skill inheritance or turned into combat manuals.
** Rearmed and Attuned Heroes cannot be used for normal skill inheritance or turned into combat manuals after using their Arcane/Elite Inheritance unless their Arcane/Elite Inheritance is restored via merges.
Alfonse: Prince of Askr, 
Sharena: Princess of Askr, 
Anna: Commander, and 
Forma units cannot be used for skill inheritance or turned into combat manuals.**
Rearmed and 
Attuned Heroes cannot be used for normal skill inheritance or turned into combat manuals after using their Arcane/Elite Inheritance unless their Arcane/Elite Inheritance is restored via merges.Availability[ | ]
Summoning events
| Start | End | Event | Skill |
|---|---|---|---|
| 2020-06-05 | 2020-06-30 | Book IV Mid: Mirabilis and More | Water Boost 3 |
| 2023-07-07 | 2023-08-07 | Summer Firsts | Water Boost 3 |
| 2023-11-17 | 2023-12-07 | Attuned Nino & Ginnungagap | Water Boost 3 |
| 2023-11-22 | 2023-12-21 | Focus: Double Special Heroes | Water Boost 3 |
| 2023-12-14 | 2024-01-14 | Holiday Lessons | Water Boost 3 |
| 2024-01-30 | 2024-03-05 | Special Hero Summon (Year 7) | Water Boost 3 |
| 2024-02-25 | 2024-03-05 | 7th Anniversary Special Focus 3 | Water Boost 3 |
| 2024-04-11 | 2024-04-25 | Focus: Double Special Heroes | Water Boost 3 |
| 2024-04-15 | 2024-05-08 | New Heroes & Attuned Azura | Water Boost 3 |
| 2024-04-30 | 2024-05-14 | Mythic Heroes - Loki | Water Boost 3 |
| 2024-06-07 | 2024-06-28 | Attuned Micaiah & Sothe | Water Boost 3 |
| 2024-06-12 | 2024-06-28 | Double AHR: Bottom Height | Water Boost 3 |
| 2024-07-07 | 2024-07-24 | Focus: New Power | Water Boost 3 |
| 2024-07-09 | 2024-07-16 | Summer Firsts | Water Boost 3 |
| 2024-07-11 | 2024-07-25 | Legendary & Mythic Hero Remix 2 | Water Boost 3 |
| 2024-08-30 | 2024-09-13 | Legendary Heroes - Shez | Water Boost 3 |
| 2024-09-06 | 2024-10-04 | Icy Invitation | Water Boost 3 |
| 2024-09-13 | 2024-09-27 | Ascendant, Rearmed & Attuned | Water Boost 3 |
| 2024-09-23 | 2024-10-04 | Aided Heroes: ω Special Heroes | Water Boost 3 |
| 2024-09-27 | 2024-10-15 | Emblem Sigurd: Of the Holy War | Water Boost 3 |
| 2024-10-11 | 2024-10-25 | Ascendant, Rearmed & Attuned | Water Boost 3 |
Distributed units
- Berkut: Prideful Prince (×1)
- Berkut: Prideful Prince (×2)
- Heroic Feats, Round Two (×1)
- Use Heroic Grails (×20)
- GHB Elite 2 quest (April 2018) (×1)
- Grand Hero Battles quest (December 2017) (×1)
Combat Manuals
| Start | End | Hero | Currency |
|---|---|---|---|
| 2021-04-05T03:00:00Z | 2021-05-28T06:59:59Z | Mustafa: Plegian Champion | Divine Code: Ephemera 4 |
| 2024-03-06T05:00:00Z | Ginnungagap: Ruler of Nihility | Divine Code: Part 5 |
Seal acquired from[ | ]
Tempest Trials reward[ | ]
- Tempest Trials+: Before We Met... ( – ): 10,000 Score.
Sacred Seal Forge[ | ]
- Water Boost 1: Create for 20 Great Transparent Badge, 100 Transparent Badge, 20 Sacred Coin.
- Water Boost 2: Enhance for 60 Great Transparent Badge, 200 Transparent Badge, 50 Sacred Coin.
- Water Boost 3: Enhance for 400 Great Transparent Badge, 1000 Transparent Badge, 100 Sacred Coin.
In other languages[ | ]
| Language | Name |
|---|---|
| Japanese | 生命の静水 |
| German | Wasserschub |
| Spanish (Europe) | Hidrovitalidad |
| Spanish (Latin America) | Hidrovitalidad |
| French | Boost apaisant |
| Italian | Impulso acqua |
| Traditional Chinese (Taiwan) | 生命靜水 |
| Portuguese | Hidrovital |