In The Eye of Chaos

[BreathWeapon]

"Whenever a player plays an instant spell, counter it unless that player pays X, where X is its converted mana cost."

1) Do multiples of this card have a comunaltive effect?
2) Does this card increase the casting cost of the instant?
3) Does this card combined with Trinisphere cause an instant to be a minimum of 3cc to cast and an additional 3 colorless to resolve?
4) Does this card combined with Sphere of Resistance cause an instant (Swords to Plowshares) to cost 1W and an additional 2 colorless to resolve?

[Jacob Orlove]

Converted mana cost = the number in the upper right hand corner (converted to colorless). Always. If the casting cost includes an  X, the X itself may change, but you still add up those numbers the same way.

1) yes, it is cumulative, because it's a triggered ability
2) no. see above
3) no. see above. trinisphere changes the total cost to play a spell, while this counters the spell unless they pay X. If the spell costs less than 3, they have to pay 3+X (or just 3 if they don't care about the spell actually resolving). If it costs 3 or more, they pay X+X.
4) no. see above. With 2sphere out, swords costs 1W to play, and an additional 1 if you want it to resolve.

[Pyromaniac]

Actually, having multiples in play would be a small wonder, because it's an enchant world, or as it's called today, a 'world enchantment'. So question 1 is kinda irrelevant

[BreathWeapon]

Actually, having multiples in play would be a small wonder, because it's an enchant world, or as it's called today, a 'world enchantment'. So question 1 is kinda irrelevant

What is the difference between Enchantment and Enchant World?

[Jacob Orlove]

Just a supertype, for which the following state based effect applies:

420.5i If two or more permanents have the supertype world , all except the one that has been a permanent with the world supertype in play for the shortest amount of time are put into their owners' graveyards. In the event of a tie for the shortest amount of time, all are put into their owners' graveyards. This is called the "world rule."