Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: Magic: the Gathering - Dark Ritual - Mercadian Masques
Product description: Magic: the Gathering is a collectible card game created by Richard Garfield. In Magic, you play the role of a planeswalker who fights other planeswalkers for glory, knowledge, and conquest. Your deck of cards represents all the weapons in your arsenal. It contains the spells you know and the creatures you can summon to fight for you. Card Name : Dark Ritual Cost : B Color : Black Card Type : Instant Card Text : Add BBB to your mana pool.
Product feature: A single individual card from the Magic: the Gathering (MTG) trading and collectible card game (TCG/CCG)., This is of Common rarity., From the Mercadian Masques set.
Product price: $1.06
Product brand: Magic: The Gathering
Target attributes: Game
Answer: attribute: game
value: planeswalker
source: product description
attribute: game
value: magic: the gathering
source: product brand
attribute: game
value: magic: the gathering
source: product description
attribute: game
value: planeswalkers
source: product description
attribute: game
value: magic: the gathering
source: product title
attribute: game
value: magic: the gathering
source: product feature