2019-01-25 : If a permanent has {X} in its mana cost, X is considered to be 0.

2019-01-25 : Kaya’s last ability causes you to gain life equal to the number of cards the target player owns in exile, even if an effect causes her to deal more or less than that amount of damage to that player.

2019-01-25 : Tokens that aren’t a copy of something else don’t have a mana cost. Anything without a mana cost normally has a converted mana cost of 0.