Artifact, XX (0) Chalice of the Void comes into play with X charge counters on it. Whenever a player plays a spell with converted mana cost equal to the number of charge counters on Chalice of the Void, counter that spell.
Illus. Mark Zug
12/1/2004: A mana cost of {X}{X} means that you pay twice X. If you want X to be 3, you pay 6 mana to play Chalice of the Void.
12/1/2004: The number of counters on Chalice of the Void matters only at the time the spell is played. Changing the number of charge counters on Chalice of the Void after a spell has been played won't change whether the ability counters the spell. If the Chalice had the correct number of counters when the spell was played, it counters the spell. If the Chalice had too many or too few counters when the spell was played, the Chalice's ability didn't trigger.
12/1/2004: If there are zero charge counters on Chalice of the Void, it counters each spell with a converted mana cost of 0.
12/1/2004: Chalice of the Void has to be in play at the end of playing a spell for the ability to trigger. If you sacrifice Chalice of the Void as a cost to play a spell, its ability can't trigger.
Mirrodin
(Rare)