Some have been in Duel Masters for a while already, like Jace the Mind Sculptor, Emrakul the Aeons Torn, Black Lotus, Nicol Bolas, and Serra Angel, and so these are reprints of their previous Duel Masters' appearances
Cloudstone Curio is the first of those cards
Im pretty skeptical, though
I'll use Muldrotha, the Gravetide as a deckbuilding example on figuring out the ratio of lands and ramp: Lands For figuring our lands, the two questions you need to ask yourself is: What's the average cmc of my spells
Chart shows the price of Te Ka - Heartless [Foil] #192 at the end of each month going back as long as we have tracked the item.
One exception to note is Uncommon cards, which are represented by the rarity symbol of an open book - the logic being that an open book has two sides, or pages