Magic: The Gathering Comprehensive Rules Changes - Shards of Alara to Conflux

Old rule (Shards of Alara)	New rule (Conflux)
406.6. [Click to view all changes.]
406.6. If a mana ability would produce one or more mana of an undefined type, it produces no mana instead. Example: If you control no lands, an ability that reads "{T}: Add to your mana pool one mana of any type that a land you control could produce" will not produce any mana.	406.6. If a mana ability would produce one or more mana of an undefined type, it produces no mana instead. Example: Meteor Crater has the ability "{T}: Choose a color of a permanent you control. Add one mana of that color to your mana pool." If you control no colored permanents, playing Meteor Crater's mana ability produces no mana.

Old rule (Shards of Alara)

New rule (Conflux)

406.6.

If a mana ability would produce one or more mana of an undefined type, it produces no mana instead.

Example: If you control no lands, an ability that reads "{T}: Add to your mana pool one mana of any type that a land you control could produce" will not produce any mana.

406.6.

If a mana ability would produce one or more mana of an undefined type, it produces no mana instead.

Example: Meteor Crater has the ability "{T}: Choose a color of a permanent you control. Add one mana of that color to your mana pool." If you control no colored permanents, playing Meteor Crater's mana ability produces no mana.