Simply put, a deck was made that abused the item, a lot. It consistently had over 30 fire elementals in play by turn 3.
Also, in retrospect, whether or not the item was broken, it was far too powerful for it's level. Consider the other summoning items put 1 character into play per turn and have other limitations.
Anyway, here is the new version, which is more in line with what the other nightmare set items are like. I apologize to those who were looking forward to using it. I'm not perfect.
For those curious: The original nightmares breath said: Order: Destroy all nightmare set items in play: Summon X fire elementals into play in your front rank, where X is the number of items destroyed.
While reviewing, I decided that probably wasn't all that good so I changed it to a spend order and got rid of the item destruction. That turned out to be over powered.
I thought about it a lot and decided that the wizard item should not move away from what the other nightmare set items do (They are all anti-summon abilities) and thus, nightmares breath has a completely new ability.