All Astromons have a grade ranging from 1 to 6, indicated by the number of stars () they have. Astromons begin at different grades, but all can be ascended up to grade 6. An Astromon's grade determines its max level. This starting level is commonly referred as the Nat-level (abbreviated from "Natural level") of Astromon so for example Fire Miho is a Nat3, because Fire Miho naturally exists as a three-star Astromon.
You can ascend Astromons to higher grades, increasing their max level. Additionally, when ascending an Astromon to 3 and 5, they will learn passive skills that bolster their basic and active skills, respectively. However, take note that ascending an Astromon will reset its level to 1.
To perform an ascension, the Astromon must be fully leveled up, and you must have enough Starstones and Elemental Stones. Starstones can be obtained from the Starstone Dungeon, and Elemental Stones from their respective Elemental Dungeon. The shady shop sells some too.
The table below illustrates the resources required to ascend an Astromon to the next grade.
|Ascension from||Starstones||Elemental Stones||Gold||Notes|
|[Low] x1||-||10,000||Max level: 10 -> 20|
|[Low] x5||-||30,000||Max level: 20 -> 30
Unlocks a passive for the Normal Skill
|[Low] x30||[Low] x10||100,000||Max level: 30 -> 40|
|[Mid] x30||[Low] x30||300,000||Max level: 40 -> 50
Unlocks a passive for the Active Skill
|[High] x50||[Mid] x50||1,000,000||Max level: 50 -> 60|
Players can convert low grade stones to higher grade stones through Stone fusion. This process consumes the low grade stone and requires gold. Stones can only be converted into higher grades, they cannot be converted into lower grades.
Stone fusion can be found by clicking on an Astromon > Ascension > Stone Fusion.
In order to fuse a stone, click on it's lesser version and then click "fuse". Ex: For a [Mid] Lightstone you would click on the [Low] Lightstone icon.
Conversion Costs & Requirements
|[Low] x10||→||[Mid] x1||5,000|
|[Mid] x10||→||[High] x1||20,000|
|*Note: Fusion cost is the same for every element|
Ascending to 3 will unlock a passive for your Normal Skill and Ascending to 5 will unlock a passive for your Active Skill. Both passives vary according to the Astromon and its element.
After an ascension completes, the Astromon's level will reset back to one, and its stats will temporarily decrease. However, its stat potential will be higher, for the same Astromon level, the higher the grade the higher the stats. Note that leveling will be harder with an higher grade (Check the Experience page for more details).