My opponent cast Hour of Eternity with X = 4, and 4 creature cards in his graveyard. In response, I Aftermathed Refuse // Cooperate to copy the spell, but I only have 1 creature card in my graveyard. What happens?
Cooperate puts a copy of the spell on the stack, the spell will have the same targets as the original spell. You can change those targets to new targets, however since you only have 1 creature card in your graveyard you can only change one of the targets. If you do so your copy will resolve, but since only one of those targets is legal it will exile the creature card from your graveyard giving you a single 4/4 zombie token. Your opponents Hour will then resolve exiling his 4 creature cards and getting 4 tokens.
Based on the last sentence of rule 114.6a, if you can't change all of the targets, then none end up being changed. In this case, that means that since you are unable to change all 4 targets, they all remain the same. Then, the spell will be countered on resolution since none of its targets are legal.
114.6a. If an effect allows a player to "change the target(s)" of a spell or ability, each target can be changed only to another legal target. If a target can't be changed to another legal target, the original target is unchanged, even if the original target is itself illegal by then. If all the targets aren't changed to other legal targets, none of them are changed.
Based on the last sentence of rule 114.6a, if you can't change all of the targets, then none end up being changed. In this case, that means that since you are unable to change all 4 targets, they all remain the same. Then, the spell will be countered on resolution since none of its targets are legal.
114.6a. If an effect allows a player to "change the target(s)" of a spell or ability, each target can be changed only to another legal target. If a target can't be changed to another legal target, the original target is unchanged, even if the original target is itself illegal by then. If all the targets aren't changed to other legal targets, none of them are changed.
Thanks for directing me to that section of the rules. However, if I'm reading it correctly, it looks like 114.6d is the relevant rule:
114.6d If an effect allows a player to “choose new targets” for a spell or ability, the player may leave any number of the targets unchanged, even if those targets would be illegal. If the player chooses to change some or all of the targets, the new targets must be legal and must not cause any unchanged targets to become illegal.
That leads me to believe Segoth's response is correct, since Cooperate uses the text "choose new targets".
Based on the last sentence of rule 114.6a, if you can't change all of the targets, then none end up being changed. In this case, that means that since you are unable to change all 4 targets, they all remain the same. Then, the spell will be countered on resolution since none of its targets are legal.
114.6a. If an effect allows a player to "change the target(s)" of a spell or ability, each target can be changed only to another legal target. If a target can't be changed to another legal target, the original target is unchanged, even if the original target is itself illegal by then. If all the targets aren't changed to other legal targets, none of them are changed.
Thanks for directing me to that section of the rules. However, if I'm reading it correctly, it looks like 114.6d is the relevant rule:
114.6d If an effect allows a player to “choose new targets” for a spell or ability, the player may leave any number of the targets unchanged, even if those targets would be illegal. If the player chooses to change some or all of the targets, the new targets must be legal and must not cause any unchanged targets to become illegal.
That leads me to believe Segoth's response is correct, since Cooperate uses the text "choose new targets".
Can anyone confirm or refute?
I think you may be right and I was misreading "change the targets" as "choose new targets". The only thing I am not sure about is the last sentence there that says "must not cause any unchanged targets to become illegal". Leaving the original targets unchanged does not cause them to "become" illegal (they are already illegal). Since it doesn't cause them to become illegal, it seems that Segoth's response is indeed correct.
Thanks for directing me to that section of the rules. However, if I'm reading it correctly, it looks like 114.6d is the relevant rule:
That leads me to believe Segoth's response is correct, since Cooperate uses the text "choose new targets".
Can anyone confirm or refute?