The new FAQ errated Snotling Invasion to make it unique. Am I the only one who thinks that doing so is a bit much? Getting more than one out a turn is a big deal for the orcs, but it is not game breaking. For the card to burn a zone was a slow burn of 4 turns anyway without any development sacrificing.
I can understand some viewing having multiple snotling invasion happening on a turn as unfair, and for that reason I can see making it limited. However, making it unique really kills the potency of the card. If one is out the opponent who has it can basically ignore the card. With a couple of sacrificing of developments the zone can be kept alive for a good while and once it is burning the Snotling Invasion is dead, and the orc player has no way to clear it out of the zone.