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

2019-01-25 : To double a player’s life total, that player gains as much life as needed so that their life total is twice the number it was before. If their life total was negative, that player loses as much life as needed so that their life total is twice as far below 0 as it was before. Other effects interact with this life gain or loss accordingly.