Mana Position is a new position introduced in Yu-Gi-Oh! NEXUS in which a card is placed right diagonally, and cannot be face-down/set. This position allows a monster to generate Mana depending on their attribute. (For example: a FIRE Monster would generate FIRE Mana). Using this Mana allows a Monster to Special Summon another Monster of the same Attribute from your Main Deck or Extra Deck, regardless of its Level/Rank.
Mana can only be generated up to the Level/Rank of the Monster. (For example: a Rank 5 LIGHT Monster can only generate up to 5 LIGHT Mana).
Any type of Monster (including Normal, Effect, Ritual, Fusion, Synchro, Xyz, Pendulum, and Nexus Monsters) can be in Mana Position, but it must be Summoned how it normally would. A Monster can be Normal Summoned and Special Summoned in face-up Mana Position.
If a non-Nexus Monster has more than one attribute (such as Elemental Mistress Doriado), it can only generate Mana of the attribute that is on the top right corner of the card (so Elemental Mistress Doriado can only generate 3 LIGHT Mana). However, a Nexus Monster (which has 2 or more attributes) has a specific amount of Mana that it can generate for each of its Attributes, which is written in the same line as the Monster's ATK/DEF Value. (For example: a Level 7 WATER-FIRE Monster could generate 4 WATER Mana and 3 FIRE Mana, or 6 WATER MANA and 1 FIRE MANA).
For a Nexus Monster to be Summoned, it needs a specific amount of each Attribute of Mana that is written on their card. (For example: an Level 4 EARTH-FIRE Nexus Monster may need 3 EARTH MANA and 1 FIRE Mana to Nexus Summon, or 2 EARTH Mana and 2 FIRE Mana to Nexus Summon).
Nexus Monsters are the only Monsters to generate more than one type of Mana, unless a Monster Effect says otherwise.
A Nexus Monster's Mana Value is how much and which Mana the card can generate, and Mana Cost is how much and which Mana the card needs to get Nexus Summoned.
Like other Monsters, the sum of the Mana Cost is the sum of the card's Level. The sum of the Mana Value is also the sum of the card's Level.