If an effect would cause Acrobatic Cheerleader's ability to trigger again, that part of the effect won't do anything
First of all, nothing is threatened
OP08-084-jack is the newest addition to Rob Lucci's control strategy
Reaver Titan Reaver Titan is massive as a 10/10 vehicle that deals 5 damage when it attacks, and it has nice, relevant protection from cheap removal and creatures
Secondly, as a small winter set packed with unique cards that are practically dripping with combo potential, Aether Revolt is likely to end up with a bunch of cards that dont quite have the necessary pieces to make it in Standard, only to show up in other formats down the road as folks figure out the most efficient combo shells
Like Atarka's Command this thing can be pretty devastating