Sidians can be made stronger for battle by improving their AK and HP stats. These stats improve with experience and levels. Fusions combining cards will the increase the max level until you reach the max fusion. (Note: there is no extra benefit for levelling up the same card separately and waiting).
An individual card starts off with different "level 1" stats, depending on the sidian's rarity. Each card also has a max level, which also depends on the sidian's rarity:
- Normal (★): Max. level is 40
- Uncommon (★★): Max. Level is 50
- Rare (★★★): Max. level is 70
- Rare+ (★★★★): Max. level is 90
- S. Rare (★★★★★): Max. level is 100
When choosing which "victim sidians" will be used in the fusion, it doesn't matter the order; this mean that you can choose an already leveled up sidian as fusion material, and the result will be the same as choosing it as the base card. The stats, progression of levels, and upgrades in the skill will transfer to the result of fusion.
If you reach the current max level the sidian have, the progress bar will not increase more, and will display a "MAX" instead of the percentage of experience; therefore, if you fuse something with the sidian in this case, nothing will happen. In order to unlock the next levels, you must upgrade their Fusion Levels.
The fusions amount improve the available levels a sidian can be upgraded, which is needed to get their maximum stats. The range of this starts at 1, which is the fusion amount that every sidian has when contracted, and goes to a maximum amount, which is relative to the rarity of the sidian, being:
- Normal (★): Max. Fusion level is 6/6
- Uncommon (★★): Max. Fusion level is 8/8
- Rare (★★★): Max. Fusion level is 8/8
- Rare+ (★★★★): Max. Fusion level is 8/8
- S. Rare (★★★★★): Max.Fusion level is 4/4
- Note that some sidians that are Rare+ or S.Rare, without upgrading fusion levels, MAX exp. is at either 40 or 60. The above info only is the level at max potential in fusion upgrades.**
Reaching the next fusion amount will unlock more levels for the sidian to increase, and have better stats. Reaching the max Fusion level allows access to the maximum level of the sidian, and to their maximum stats. Once the Maximum Fusion level is reached, the fusion won't have any other effect, but give some experience if the max level hasn't been reached.
This fusion can be performed by fusing copies of the sidian, or using Special sidians as fusion material, such as:
If you reach the max fusion amount the sidian can reach, fusing more won't have more effect other that increase the level of the sidian, and if this level already is maxed, fusing won't do any other effect.
As you level up, the sidian's appearance will transform automatically. The required level for transformation depends on rarity.
When reaching this level, an animation will be shown: putting the sidian in a papire, then writing the name "Lussid" below it, then, will show the new appearance with a "Make Up" title. This feature is only available for RARE sidians or higher. The Forms are also related to the rarity of the sidians:
- RARE sidians have the 2nd form when reaching level 30, and will have the 3rd ultimate form when reaching the maximum level.
- RARE+ and S. RARE sidians have the 2nd form when reaching level 40, and will have the 3rd ultimate form when reaching the maximum level.
Once the next form is reached, it cannot return to the previous appearance. Most sidians can reach the 2nd form without needing to increase their Fusion level, since their natural (starting) form usually has the current max level required for the change of appearance.