If a card in your graveyard has {X} in its mana cost, X is 0 when determining that card's mana value.
23-07-2021
wotc
Although land cards aren't considered, nonland cards with mana value 0 are. For example if the cards in your graveyard are an artifact card with mana cost {X} and a sorcery card with mana cost {2}{U}, you'll draw two cards.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.