unmask and chalice of the void

[jamestosetti]

Can you play unmask with a chalice set on zero?

[Godder]

Yes, because Chalice of the Void has a triggered ability. If the question is "will Chalice of the Void @ 0 counter an Unmask?" the answer to that question is that it won't, because Unmask's converted mana cost is 4, not 0. Chalice cares about the converted mana cost (the total cost in the top right corner of a card), not how much was actually paid for a spell.

[jamestosetti]

Thanks. I know about the converted mana cost of a card but I did not know if the mana cost was zero because you have the option to remove a card instead of paying four I think it is.

[Clariax]

Mana Cost is the symbols in the upper right hand corner.  Converted Mana Cost is the whole number you get if you add up all those symbols.  So in the case of Unmask, the Mana Cost is  and the Converted Mana Cost is 4.  (Note that it's 4, not  .)  This is what these values always are.  They may have little to no correlation with how much is actually paid to play the card.  How much you must pay to play the spell in a given situation would be the cost to play the spell.  It's very rare that a card will care about this (see Trinisphere for an example).
 

Thanks. I know about the converted mana cost of a card but I did not know if the mana cost was zero because you have the option to remove a card instead of paying four I think it is.

[jamestosetti]

Trinishpere would make the unmask cost 3 then wouldn't it? If there is a trinisphere and a sphere of resistance in play then the cost is 4?

[Anusien]

You apply cost increasers, then cost reducers, then Trinisphere.  So Unmask paying the alternate casting cost with Trinisphere and Sphere of Resistance out still costs .