Rebirth (転醒; Tensei) is the main gimmick of the 11th saga of Battle Spirits, introduced in SD55. Cards which possess the keyword are printed on both sides, each side having their own effects, cost, and even differing card types. While some Rebirth cards do not have it, Rebirth serves mostly as a "remains on field" effect, as one of the general conditions for the flipping is for the opponent to remove the card from the field, through effects for Nexuses, via any means for Spirits.
The primary condition for Rebirth are counters, having less than a certain number allows the card to flip once they meet the condition, and when a card is Reborn, it adds a counter, making it so the more Rebirths are used, closer the player is to be unable to use them.
Meanwhile, Zero Rebirth (零転醒, Zero Tensei) requires the player to have zero counters to activate, and adds no counters upon flipping, conflicting directly with vanilla Rebirth, making it so the synergy with Rebirth and counter-based decks is nearly non-existing.
Texts possible for Spirit Rebirths include:
- Rebirth: X or less Counters (Only one Rebirth can be used at a time) When either (Condition A) or this Spirit leaves the field due to the opponent, put on this Spirit and it is Reborn.
And for Nexus Rebirths, there is:
- When either (Condition A) or when opposing effects would remove this Nexus from the Field, you can put on this Nexus and it is Reborn.
- When (Condition A), this Nexus can be Reborn. When it is, you can put one core from your Field/Reserve to this now-Reborn Spirit.
Once flipped, the Reborn side contains the following text:
- When you flip into this side, this card remains on the field, and you gain a counter. (Put a core from the Void to your Counter Area.)