Nightmare is the name given to the Gacha system of the game. The player is presented with multiple pools to 'summon' in, which will all yield different rewards. There are three basic pools: Chapter A, Chapter M, and Chapter G. There are also Event Nightmares that are available for a limited amount of time.
In order to summon in an Event Nightmare, Chapter A, or Chapter M, the player must spend 30 Devil Points or 1 Demon Voucher to summon once, and 270 Devil Points or 10 Demon Vouchers to summon 10 times. When doing a x10 summon in these pools, an SSR or higher card is guaranteed. Chapter G requires the player to spend 3,000 Grimm or 27,000 Grimm in order to summon once or ten times respectively.
The player is awarded a free summon once every 48 hours in Chapters A and M, and one once every 24 hours in Chapter G. For VIP members, these times are halved to once every 24 hours in Chapters A and M, and once every 12 hours in Chapter G.
|Event Nightmares, Chapter A, and Chapter M Summon Rates|
|Chapter G Summon Rates|
- In the game's tutorial, it was mentioned that Nightmare is a magic book app (aka a grimoire app), and that the Royal Library of the Devildom is in charge of it.