| 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 boost that can be applied during combat 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 5  | Water Boost 2 5 | Water Boost 3 5 | Diluvial Boost 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 | Primordial Boost 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 | Diluvial Boost 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 |
| 2024-11-11 | 2024-11-25 | Legendary & Mythic Hero Remix 1 | Water Boost 3 |
| 2024-12-20 | 2025-01-03 | Focus: Double Special Heroes | Water Boost 3 |
| 2024-12-25 | 2025-01-04 | Holiday Lessons | Water Boost 3 |
| 2025-01-23 | 2025-02-06 | New Heroes Return | Water Boost 3 |
| 2025-02-02 | 2025-03-07 | Special Hero Summon | Water Boost 3 |
| 2025-02-15 | 2025-02-25 | 8th Anniv. "12 Luminaries" 2 | Water Boost 3 |
| 2025-02-27 | 2025-03-09 | Focus: Heroes with Boost Skills | Water Boost 3 |
| 2025-04-04 | 2025-05-06 | Precious Siblings | Water Boost 3 |
| 2025-04-20 | 2025-05-06 | 35th Anniv.: Rising Heroes Summon 2 | Water Boost 3 |
| 2025-05-07 | 2025-06-06 | New Heroes & Rearmed Dedue | Water Boost 3 |
| 2025-06-08 | 2025-06-13 | Revival: Attuned Nino & Ginnungagap | Water Boost 3 |
| 2025-06-13 | 2025-06-18 | Revival: New Heroes & Att. Azura | Water Boost 3 |
| 2025-06-15 | 2025-06-20 | Revival: Attuned Micaiah & Sothe | Water Boost 3 |
| 2025-07-15 | 2025-07-25 | Summer Firsts | Water Boost 3 |
| 2025-08-11 | 2025-08-14 | Focus: Heroes with Boost Skills | Water Boost 3 |
| 2025-08-29 | 2025-09-15 | Legendary Heroes - Diamant | Water Boost 3 |
| 2025-09-08 | 2025-09-18 | Icy Invitation | Water Boost 3 |
| 2025-09-13 | 2025-09-27 | New Heroes Return | Water Boost 3 |
| 2025-09-24 | 2025-10-07 | Entwined Hero "12 Luminaries" 2 | Water Boost 3 |
| 2025-10-21 | 2025-11-04 | Focus: Double Special Heroes | Water Boost 3 |
| 2025-10-25 | 2025-11-08 | Focus: New Heroes Return | Water Boost 3 |
| 2025-11-12 | 2025-11-26 | Legendary & Mythic Hero Remix 2 | Water Boost 3 |
| 2025-11-25 | 2025-12-08 | Focus: Heroes with Savior Skills | Water Boost 3 |
| 2025-12-21 | 2026-01-01 | Focus: Resounding Hearts! 1 | Water Boost 3 |
| 2025-12-25 | 2026-01-01 | Winter Festival: ω Special Heroes | Water Boost 3 |
| 2026-01-21 | 2026-02-01 | Revival: Rearmed Dedue & More | Water Boost 3 |
| 2026-01-24 | 2026-02-07 | New Heroes Return | Water Boost 3 |
| 2026-02-02 | 2026-03-06 | Special Hero Summon (Year 9) | Water Boost 3 |
| 2026-02-27 | 2026-03-16 | Mythic Heroes - Tiki: Everlasting Voice | Water Boost 3 |
| 2026-03-28 | 2026-04-02 | Focus: 3,333rd Day Anniv. 9 | Water Boost 3 |
| 2026-04-01 | 2026-04-06 | Focus: 3,333rd Day Anniv. 13 | Water Boost 3 |
| 2026-04-11 | 2026-04-21 | Precious Siblings | Water Boost 3 |
| 2026-04-30 | 2026-05-18 | Leg. Lyon & Myth. Sombron | Water Boost 3 |
| 2026-05-27 | 2026-06-05 | Focus: Claimed by Darkness | Water Boost 3 |
| 2026-06-13 | 2026-06-18 | Revival: Rearmed Dedue & More | 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 | |
| 2025-03-06T05:00:00Z | Micaiah: Dawning Maiden | Divine Code: Part 6 |
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 |