Ok recently this came up and i thought it woud work the other way, but according to the rules i may be wrong.
If you play a card with an additional cost, in this case lets say The Anti K, and you fail the CC, do you still pay the cost?
If you are going 2nd, your opponent plays their first card at 3 difficulty, checks a 3, then you R with action side of the anti K, and flip a 2....do you still put a card from your hand into your card pool face down?
Another example could be playing KFT as an action R and failing the CC, do you still commit 2 foundations?
I always thought additional costs were paid AFTER the cc was passed, but was told that it is simultaneously and independent to pay the costs regardless of wether or not you pass CC.
Thanks