The Rebirth upgrade option is found in-game under "Upgrade" then selecting the "Awakening" tab. There is a new area under Awakening called "Rebirth". Unlike Awakening which uses 4 or 5 items types to upgrade, Rebirth can use up to 3 different item types to perform the Rebirth. So far all rebirth cards only have a single item type that they need.
The in-game help describes Rebirth as follows:
- According to a recently discovered ancient book, there is a secret alchemy called [Rebirth] that can awaken a maiden's true hidden power. A rebirth can upgrade the powers of some awoken maidens using special items that carry magical powers. This secret alchemy has been forbidden until now. This supreme power does not only greatly increase a maiden's ability but it also amplifies her skill. Although only a few chosen maidens can perform a rebirth, using a newly discovered special item can guarantee a success! Please keep on upgrading and eventually, the maidens who can perform a rebirth would gradually increase. The special items that carry magical powers needed for Rebirth are very rare and can hardly be found in Celestial Realm. Let's go forth and collect the items in Celestial and Demon Realms.
Only some cards support Rebirth. Cards that can be reborn, or reincarnated, must first be awoken. You will also need the Rebirth Items associated with the card being reborn. Each reborn card will have different requirements, so see each card info page for details.
The items for rebirth can be found during Demon Realm Voyage events in either Demon Core Exchange or as Rank Rewards. They are also sometimes available as Shop purchases requiring Jewels. You can also find them during Elemental Chronicle events from the Merchant (Petra) who shows randomly on the map. Rebirth items drop from her [Mystery Box] purchase.
To perform a Rebirth and get the best stats, you should follow the suggested Evolution & Amalgamation process for the material cards up through the H rarity (HSR, HUR, HLR). Once at the H rarity, you can then awaken at level 1 as usual, and then perform Rebirth at level 1 again.
If you are going to Max Attack and Defense, then you can apply the arcana at the H, or G rarities to help offset resource costs. Any arcana applied between H or awoken (G) rarities are kept through rebirth.
Once a card is reborn, the rarity of the card will change (GSR/GUR/GLR → XSR/XUR/XLR). In addition:
- Basic stats will increase.
- XSR Stat cap is 31,999.
- XUR Stat cap is 44,999.
- XLR Stat cap is 200,000.
- Level cap will also also increase.
- Level 90 for XSR.
- Level 110 for XUR.
- Level 130 for XLR.
- Skill will change.
- Increased awoken burst turns.
- 4 turns for XSR and XUR
- 7 turns for XLR
- Increased soldier up rate during awoken burst.
- +300% for XSR and XUR
- +400% for XLR
- Increased maximum damages for tower and Demon Realm Voyage events.
- 20,000,000 for XSR/XUR
- 40,000,000 for Event Summon XUR during their event
- 60,000,000 for XLR
- Increased damage dealt to the KO Gauge.
All stats gained from evolution/amalgamation and arcanas added before rebirth are carried over to the reborn card.
Carried Over After Rebirth
Some of the previous stats before rebirth will be carried over:
- All ATK/DEF/Soldier stats gained from evolution and Arcana.
- Affection points (friendship level).
Not carried over:
- Card level (reset to 1).
- Skill level (reset to 1).