So you're trying to defend yourself, but your opponent has too many Furres on the field for you to make a comeback. You're finished, aren't you?
Not if you've got Otherkin on your side!
You can't play Clusterfuck until there's four Furres in bed, but once you do, wham! When the dust settles, everyone is messy and ready to take a trip to the couch!
If your opponent swings with only 3 Furres, then you can put out with 1 more to make the total 4, and then lay down a Clusterfuck! You'll lose one Furre, but your opponent will still be losing 3!
"Extra requirements" are only requirements to play the card. If your opponent reacts with something that reduces the number of Furres in bed to below 4, it'll still resolve, and the remaining 3 Furres will still orgasm! After you've fulfilled the additional requirement and spent the AP and GP to play it, then the only thing that can stop a Clusterfuck is a denial card!
You can grab a Clusterfuck next month when 2nd Vanilla comes out!