2018-03-16 : If a card in your library has {X} in its mana cost, X is considered to be 0.

2018-03-16 : You can find any number of creature cards, so long as their total converted mana cost is 6 or less. For example, you could find eight creature cards with converted mana cost 0 and three with converted mana cost 2, but you couldn’t find two with converted mana cost 4.