Kat's tail impacted Xiao just below the waist on his right side. His aura of qi flared in response, screeching like nails on a chalkboard as it cracked and buckled under Kat's strike. When the qi dimmed once more, Kat's own fire seemed to flare up eagerly in response, shattering the already breaking barrier and sending Xiao flying.
Kat found herself pitching forward, that one strike had eaten up a full ten percent of her reserves by itself, and without having Xiao there to counterbalance the weight she was throwing around, she had no choice but to pitch forward. Even her normally ever ready tail had been used in the strike, and so it was only by a panicked flap of her wings that she managed not to simply faceplant into the ground.
