Chalice of the Void

Set
Masters 25
Rarity
Mythic
Text
Chalice of the Void enters the battlefield with X charge counters on it. Whenever a player casts a spell with converted mana cost equal to the number of charge counters on Chalice of the Void, counter that spell.
Legality
Legal in: Commander, Duel, Legacy, Modern
Restricted in: Vintage
Rulings
2018-03-16: A mana cost of means that you pay twice X. If you want X to be 3, you pay to cast Chalice of the Void.

2018-03-16: The number of counters on Chalice of the Void matters only at the time the spell is cast. Changing the number of charge counters on Chalice of the Void after a spell has been cast won’t change whether the ability counters the spell.

2018-03-16: If there are zero charge counters on Chalice of the Void, it counters each spell with a converted mana cost of 0. This includes face-down creature spells cast with morph’s alternative cost.

2018-03-16: Chalice of the Void has to be on the battlefield at the end of casting a spell for the ability to trigger. If you sacrifice Chalice of the Void as a cost to cast a spell, its ability can’t trigger. However, if it leaves the battlefield once its ability has triggered, that ability will still counter the spell.