Sphere of Annihilation - Adventures in the Forgotten Realms Promos

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.