They are similar to the Pendulum Monsters introduced in Yu-Gi-Oh! ARC-V, in which they are both Monster Cards and Spell Cards. This is supported that there are Mana Monster versions of Extra Deck monsters, including Fusion and Synchro. However, they are very much different from Pendulum Monsters in several ways. First and foremost, they are always treated as Normal Spell Cards when the Duel begins, meaning they cannot be Summoned or Set from the hand as monsters. (This is referenced by Mana Monsters’ green half being noticeable on the top, as opposed to the bottom like Pendulum Monsters.) In this case, a Mana Monster’s Mana Effects will be applied, including the condition of giving them an alternate name, as opposed to their Monster Effects (if any). Although they are treated as Spell Cards firsthand, their activation and effects cannot be negated by cards such as "Imperial Order" and "Spell Canceller", and cards and effects that would be activated in response to a Spell Card's activation and resolve (such as "Skilled Dark Magician" and "Curse of Darkness") cannot be activated. However, only one Mana Monster as a Spell Card can only be activated per turn. (A player is, however, allowed to Set more than one Mana Monster as a Spell Card during the same turn.)
Another noticeable difference from Pendulum Monsters is that Mana Monsters have a Mana Count as opposed to Pendulum Scales. After being successfully activated as a Spell Card, a Mana Monster will be placed face-up on the Extra Deck instead of being sent to the Graveyard. (Like Pendulum Monsters, this can cause the Extra Deck to be larger than would be allowed during Deck building.) Once face-up on the Extra Deck, the Mana Count will determine how many turns must be passed before a Mana Monster can become a Monster Card. Once that number of turns has passed, a Mana Monster can be Special Summoned from the Extra Deck through its regular Summoning method associated with its Extra Deck type (i.e. Fusion Summon for Fusion Monsters, Synchro Summon for Synchro Monsters, etc.). This Special Summon will always be treated as its associated Extra Deck Summon. However, as only one Mana Monster can be activated as a Spell Card per turn, a player can only Special Summon one Mana Monster per turn, and they can only control one Mana Monster at a time.
Unique Rulings Regarding Monster/Spell Status Edit
If a Mana Monster is removed from the field while it is a Monster Card, it will be treated as a Normal Spell Card as it was when the Duel began. The exception to this rule is if a Mana Monster is removed by a card effect that would otherwise return it to the field. Examples include:
- A Fusion Mana Monster being banished by "Paradox Fusion"; it will still be treated as a Monster Card because it will be returned to the field during the player's second End Phase.
- A Mana Monster being banished by "Destiny HERO - Doom Lord"; it will still be treated as a Monster Card because it will be returned to the field during the player's opponent's second Standby Phase.
If, however, a Mana Monster is to be returned to anywhere other than the player's field while being banished by the aforementioned cards, it will become a Normal Spell Card. Furthermore, if a Mana Monster would be sent to the Graveyard other than by being activated as a Spell Card, it will not be placed face-up on the Extra Deck, and thus will not become a Monster Card.
- Because a majority of Mana Monsters are Extra Deck monsters, they are the first Extra Deck monsters that can be stored in the Main Deck by default.
- Furthermore, with the inclusion of Ritual Mana Monsters, they are the first Ritual Monsters to be placed in the Extra Deck as well as the Main Deck.