Sphere of Annihilation
Artifact
This artifact enters with X void counters on it.
At the beginning of your upkeep, exile this artifact, all creatures and planeswalkers with mana value less than or equal to the number of void counters on it, and all creature and planeswalker cards in graveyards with mana value less than or equal to the number of void counters on it.
Jason Felix
Rulings
If a permanent on the battlefield or a card in a graveyard has {X} in its mana cost, X is 0 when determining that card's mana value.
(wotc • 2021-07-23)
Printings
Rulings
If a permanent on the battlefield or a card in a graveyard has {X} in its mana cost, X is 0 when determining that card's mana value.
(wotc • 2021-07-23)