Also unlike Mana Confluence, though, you have to have an artifact on the battlefield to use the second ability of adding a mana of any color to your mana pool, which also restricts the decks it can be maximized in to ones with artifacts
They are alternate art versions of cards in the main set, they have no borders, a special rainbow foil treatment, and a special rarity symbol
The experience counter goes on you, the player, not on Katara
Losing 3 life is a minor price in Commander, a slow format with high life totals, and anyone running Anguished Unmaking in an Orzhov-colored deck is probably gaining lots of life anyhow
BAM Pocket is for your iOS device, and it's a free-to-play release from Konami, no doubt hopeful to muscle in on the ludicrous sums of money being made off of Rage of Bahamut and its ilk